FPS Controller falls through 3D Model

Hey, I was wondering if one of you guys could help me with this! I purchased a Bunker 3D Model off the asset store and was going to use it was my spawn point in my map but my FPS Controller keeps falling through it and onto my terrain. Is there anything I can do to fix this?

Thanks!

Link to 3D Model:

@OSG is correct. Add a mesh collider. Physics => Mesh Collider