Problems regarding unbuild objects.

The project im doing original started in revit then was imported to 3dsmax and then imported to maya then imported to Unreal Engine 4. (Revit>>3DS Max>>Maya>>UE4.)
So i have a building of a storage facility. Its really big and i expect there to be lots of ****ed up meshes on the model. I began adding some collision adding light and then fooliage.
After i had done thise things my computer couldent simulate it anymore when i told it to. And yes i know i have to build, the problems i am facing is that my UE4 dosent want to build. It builds the scene and then when i simulate it in standalone on in Ue4 window it tells me i have 2000 unbuild objects. I tried fixing it by removing objects but it just made it worse so now im facing 4000 unbuild objects. As you can imagine this is a big problem as i am not able to test my scene with collision lights etc.
Pleas help me out this is a long term project!!


Best Regards
Christoffer Bjerregaard.

As the log says, you ran out of memory when baking lighting with lightmass. Reduce the resolution of lightmaps, or switch to completely dynamic lighting.

I will be upgrading ram. As my computer often says that i am in need of memory.