Orc asset (prefab) not working in unity 5.6.7

Hi, I'm new to Unity.
I downloaded a prefab element from unity asset store and I tried using it in a game I'm building, but when I insert it to the scene and add to it RigidBody and BoxCollider components and run the game, the orc exploits (the pieces that make the prefab are scattered around, not together; see attached image).
The page description says it's compatible with Unity 4.3 and higher, so I don't know what I'm doing wrong.
I'm adding the RigidBody and BoxCollider components to the first element of the orc prefab, not individually to each one of them.

 

try removing the rigidbody and box colliders to see if it fixes itself. If it does you did something wrong with those.

 

No, I tried already removing the rigid body and box colliders and when I run my game the orc still exploits.

 

try reataching the sprites and stuff?

 

I tried doing that and not it doesn't exploit, but when I play the game the orc grows a lot and then when I begin moving it grows smaller and it's head moves down, covering its body, and when I change the side it is facing, just by inverting the axis it begins at another place away from its last position.