US:
We do have condominiums. A "condo" is basically an apartment that you own (as opposed to paying rent).
The word "condo" can mean the whole building (consisting of multiple people's living spaces) or to just one person's living space (their living room, bedroom(s), kitchen, bathroom(s), other rooms - depending on the size of the place).
If someone said "you can stay at my condo." I would assume that they own a place. And that there is a spot (maybe an extra bedroom with an extra bed, maybe just a comfortable sofa) for me to sleep. It is ambiguous.
I would never say "condo room." If I wanted to specify a room, I would say "you can stay in my guest room." or "you can stay in my living room" or "you can sleep in my kitchen" (or whatever).
There's really no way that you would own the whole condominium building. That doesn't really make sense. But if you did, and there was an empty living space (with its own collection of rooms) where no one lived, you could say "I have an second condo, you could stay there."