celinanananah From your description, it sounds like you are trying to do it the wrong way. First, you can only buy an entire residential rental (RR) building, not individual apartments in one. To do that, there is a panel on the far right of the sim panel what has the RR management functions. It is the icon furthest to the right and looks like a cash register. Use that to first buy a residential rental apartment building, then manage it as the landlord. You can't buy and own the apartments in San Myshuno, Evergreen Harbor, Cuidad Enamorada or Ondarion. You can only rent them.
Hope this helps.
