Now it works, my fault. It must be a .zip file, like you said.
Sorry for bother you and thank you very much.

I tried several files from this web site, and others too.
When I try to do it by "Choose model" files are grey...not eligible. Files are .obj and .3ds.
Maybe it must be .zip???

I use the Mac App Store version 5.1.1 and OS X Yosemite 10.10.5.
I think I do what FAQ says but always the same answer "can't read the model. Choose another one".
What I do is make a library and insert it, but can't do it with objects one by one.

Hi, i use mac and can't insert new objects.
I tried .obj and .3ds and answer me that can't read the model. Choose another one...

I have no problems inserting libraries. It works well.