I hired a guy to draw some custom models for me. They are in .obj format. I can't import them. When I try to drag and drop, I get an error message; when I try to choose them from my hard drive, they are grayed out/unavailable for selection.

I'm using Version 5.2.1 Mac App Store.

He has sent me ...

I find this program pleasingly easy to use, even for a novice such as myself. Is it possible for me to hire someone to make models of furniture and other objects? I need to create a plan for a new workshop, with lots of weird stuff that isn't in the paid-for version's library.