Collision doesn't work.

I placed a capsule with a rigidbody component and a 3d model under it and the capsule keeps falling through it instead of on it.

Has the model a collider?

When I applied the collider to the model it still didn’t work.

It seams that you are using a mesh collider. Toggle on the is convex field

Is there a way to do it without putting the colliders?
This model is divided into lots of separate parts, each is used to show a different texture.

It works now.
Nevermind.