Unity has separate 2D and 3D physics systems.

3D:

Rigidbody
Collider
Physics
Collision
OnCollisionEnter
OnTriggerEnter

2D:

Rigidbody2D
Collider2D
Physics2D
Collision2D
OnCollisionEnter2D
OnTriggerEnter2D

Do not mix 2D and 3D physics components expecting them to interact.