What do you call the people who live in condominiums?

As already mentioned in the comments (the citation in support of this answer), there is no specific word in American English for people who live in / own a condominium, which is apparently “a building or complex of buildings containing a number of individually owned apartments or houses”. (The word isn’t really used in British English.)

To suggest how to translate it one would need context. For example, if it were a newspaper report you would use a phrase like:

The condominium residents (or alternatively owners?) held a meeting to decide how to…

Whereas if it were a technical document you might write something like:

The mean annual income of people living in/people owning condominiums has been shown to be 1.8 times higher than those renting apartments…

The point that needs to be clarified is whether the term “owner” is valid. I am not familiar with the financial structure of the ownership of this sort of building.

In Canada, where condominiums are common, we would likely say "condo dweller" and would also write this as well, if the writing were informal.

A Google search for "condo dweller" gives results from throughout North America, as well as the alternative "condo-dweller".