I don't have any experience with FPS Creator so I can't be of much help with it. I'm not affiliated with The Game Creators. They just gave me permission to publish this project.
The 3d first person example creates the level from the .obj files found within the media/3d_first_person_example folder. These files are pre-made 3D objects, so all the code has to do is load them and their texture image.
I don't have the 3D asset pack, but the process of loading the objects is the same.
I hope this helps!