I would be very, very careful about too facilely assuming that Eco's essay describes Clinton. In point of fact, the elements he ascribes to fascism much more comfortably fit the mold of Trump and his followers.
I am on my phone (and at work), so this will have to do. Eco summed up the elements he saw as common to fascists everywhere (inasmuch as fascists and proto-fascists have at least one of these elements):
1. The first feature of Ur-Fascism is the cult of tradition. There is no respect for tradition among Clinton, the democrats, and the left that supports her generally; to them, tradition is part and parcel of the evil that must be fought and eradicated root and branch. This can be seen quite readily in their constant attacks on religion (a traditional value in America) and in their radical advocacy for very non-traditional sexual values; people who advocate for the right of cross-dressers to use the restroom of their choice, based on their subjective sense of gender, are not traditionalists.
By contrast, one of the key pillars for Trump's supporters in particular (and more generally for Trump) is, precisely, the radical protection of all things traditional. This can be seen in the defense of traditional religion as well as the bitter opposition to any sort of consideration to any degree for non-traditional sexual attitudes, including radical opposition to the rights of two consenting adults to have homosexual relations in the privacy of their own home.
Eco also ascribes to this aspect of Ur-Fascism a syncretism, in which all of the various strains of "traditional" belief are put together, and the internal contradictions glossed over. Clinton and her followers are very intolerant of internal contradiction, which can be seen in their single-mindedness. Trump and his followers, however, seem much more comfortable with a syncretism of traditional values; for example, Trump's supporters claim to be all in favor of the traditional American value of individual liberty, while at the same time embracing a degree of anti-homosexuality, for example, that is antithetical to the traditional concept of individual liberty.
This element of Ur-Fascism describes Trump and his followers; it does not describe Clinton or her followers with any degree of accuracy.
2. Traditionalism implies the rejection of modernism. Again, this aspect of Ur-Fascism fits Trump and his supporters quite well. As stated above, Trump's supporters reject any concept of a modern view of gender, sexuality, or the rights of individuals - even within the confines of their own homes - to have freedom to step beyond the traditional concept of the nuclear family, with its stay-at-home mother who cooks, cleans, and raises the children, the hard-working father who suborns personal freedom and family time to "bringing home the bacon", and the obedient children. This can also be seen in the rejection of global trade, and even in the rejection of modern economics for a jobs program that is more in line with early to middle Twentieth Century industrialism than with the present state of affairs.
Again, this element applies to Trump and his supporters; it sits uncomfortably on the shoulders of Clinton and her followers.
3. Irrationalism also depends on the cult of action for action’s sake. This also fits very well with Trump and his supporters. His supporters call for action, action first, action foremost, and action now. Forget about thinking through current problems and trying to figure out what went wrong. One of the clearest examples is on immigration. Trump's supporters demand that he act now - first day in office type of action - to round up and deport every single illegal alien, period. They say we should enforce existing immigration laws, no matter how unjust or irrational, now, and then, once we've rounded up and deported all the illegals, maybe we can sit down and think about whether the immigration laws need to be changed. That displays not only the preference for action over thought, but also the cult of traditionalism - favoring the old (i.e., traditional) immigration laws, no matter how unjust, over any possible modernization of those laws.
This element does also fit Clinton and her supporters quite well, but their irrationalism is more that of communism and the internationalists than it is of fascism and the nationalists.
4. No syncretistic faith can withstand analytical criticism. This definitely applies to Trump's supporters, who generally respond to any sustained critique of Trump with jingoism and slogans.
Of course, it also applies to Clinton, her supporters, and leftists generally, so this is, standing by itself, most likely a neutral element that serves only to identify totalitarian systems, not just fascist systems.
5. Besides, disagreement is a sign of diversity. In spades does this apply to Trump and his supporters. Neither will brook any disagreement with the Orange God or his policies, no matter how flexible or changeable those policies are. And woe be unto anyone fool enough to point out the flip-flops.
However, this also applies generally to Clinton and the left, so again, this is most likely an aspect of totalitarianism and not simply of fascism alone.
6. Ur-Fascism derives from individual or social frustration. To continue Eco's language: "That is why one of the most typical features of the historical fascism was the appeal to a frustrated middle class, a class suffering from an economic crisis or feelings of political humiliation, and frightened by the pressure of lower social groups."
Trump's core motivating claim has been an appeal to a frustrated middle class, and one of the fundamental aspects of Trump's supporters is that they define themselves as the frustrated middle class, suffering from an economic crisis - typically, the bogieman of globalism - and feeling political humiliation - their frustrations with what they see as the depredations of Obamaism and the constant denigration of them and their values by the mainstream media. They are also - although they will not admit this - frightened by the pressure of certain lower social groups, in particular, blacks, hispanics, and immigrants.
This aspect of Ur-Fascism is a defining element of Trump and his supporters. Not so much Clinton and her supporters, who are largely frustrated by their perceived inability to wholly conquer the benighted forces of traditionalism and nationalism.
7. To people who feel deprived of a clear social identity, Ur-Fascism says that their only privilege is the most common one, to be born in the same country. This fits Trump's supporters to a tee, with their clear anti-immigrant beliefs (which extend not just to illegals, but to any immigrant who comes here and "takes" a job away from an American). This most emphatically does not fit Clinton or her supporters.
8. The followers must feel humiliated by the ostentatious wealth and force of their enemies. Notwithstanding the fact that Trump is wealthy too (claims to be a billionaire), this also tends to describe Trump's supporters, who feel they have been humiliated by the forces of globalism - including the big banks - which have arrogated to themselves immense wealth at their expense.
Clinton and her supporters also stake out positions against wealth, but they do so more from a sense of hatred and envy, not so much from a sense of being humiliated by ostentatious wealth.
That will have to do for now. As should be painfully obvious, the elements of Ur-Fascism that Eco has identified in most cases fit more easily to Trump and his supporters than they do to Clinton and her supporters. As such, I would not characterize Eco has describing for us the terrors we avoided by not electing Clinton.