RTF is a global modification that replaces all towns in the game.

I haven't played much with the Dark Dwarfs, so I don't quite understand which building allows you to recruit which units. So, is it like this: basic units - nothing, elite units - Fortress, champions - Stronghold?

I forgot about this, but in principle, with such a building tree, it's possible. I think that if a city isn't built, no units can be recruited. Dweller units will appear after building two of any huts, and the main units will only be available with a Fortress.

Added 16 minutes laterWhere is this folder? 0_o

When you create a map, this folder appears automatically inside.