Custom model with car tutorial problem

Hi all, I am encountering a problem with the car tutorial. The car doesn’t collide correctly despite me assigning the proper colliders. I followed the tutorial exactly, but no dice. Is this because of the fact that I have a custom model I am using as apposed to the one in the tutorial (the hierachy are fairly similar, but not identical). Also, I tried a third person controller for a car as a backup and the car flickers whenever it is stationary. Any fix for that either? Thank you!

when you export or import it should be in fbx format and to add colliders click it in project tab and click generate colliders.