What is the best way to import autocad models into the unit?

I just asked someone to create a 3D environment for my game in autocad 2015. I've exported this environment and I've imported it into the unit, but it does not work not correctly because I can not see my environment properly in the scene view.

Any suggestions on how to do it better? I am not good with 3D modeling and have already used autocad models in the unit before. Any help is highly appreciated. 🙂