This whole "The US is not a democracy, it's a [variable adjective] Republic" is one of the silliest, and most pervasive, memes among certain types of libertarians and right wingers.

Unless you unequivocally and totally identify "democracy" with "direct democracy", as in what happens in a referendum, the US is as much a democracy as any other Western-style so called "liberal democracy".

This is because "democracy" only refers to a method of decision making based on "one citizen, one vote" (and then you can still cheat by restricting who is a citizen, and so on and so forth, but the broad definition applies).

What happens in the US presidential elections, is exactly what happens in many other countries, where the citizens do not elect the president directly, but a group of "representatives" who are the ones who actually nominate and choose the president.

In Spain, just to give a simple example, it's the parliament who does that, and "parliamentary elections" equals "Primer Minister elections", and people go to the ballots with a " primer minister candidate" and their party in mind, not the actual representative who will vote.

In the US you choose a temporary, ad hoc group for that purpose, the Electoral College, but it's exactly the same.