Some models doesn't works

[Maldazzar]

Hi, I've downloaded a lot of models from here, but some doesn't work, they appear like a green cube in the world editor, and in the game, don't appear, please, tell me what to do, THX

 

[General Frank]

If you would point out which models seems not to work people might help you.

But this might help you for the general idea what you might be doing wrong.
https://www.hiveworkshop.com/forums/3d-modeling-tutorials-282/how-import-custom-models-32237/