Exporting a C4D model to Unreal engine

Hi! I’ve been looking for accurate tutorials, but haven’t found any yet, so here I go.

My friend is creating a 3D level in Sketchup and I’ve imported that successfully to Cinema 4D. But when I want to export it to Unreal Engine, to put it in my game, it is exported as only one 3D model, I mean, If I try to change a single texture, the whole model changes to that texture, instead of changing and individual part of the model.

Basically, what I want is to export my model from C4D r16 with the best settings and be able to change the level textures individually as I can within Cinema 4D.

ALSO, there’s another problem, when I export my level from C4D to Unreal Engine, there’s a lot of ‘parts’ missing from the model, any help, please? Thanks a lot.