Animator not showing animation

Hello,

I downloaded an older model from the Unity Asset Store that has its own animations. I believe it uses the old legacy system, because the test scene that it comes with manages to play the animations without a character controller. When I try to use the Animator and a Controller, and after I create a new state, I can’t drag the animation into the motion box, as if the animation is empty. I have my movements scripts and everything, but all of my scripts are written in c# so I don’t fully understand how they were played. What do I need to do to make these animations play in c#?

        transform.Rotate(0, Input.GetAxis("Horizontal")* rotateSpeed,0);
        Vector3 forward = transform.TransformDirection(Vector3.forward);
        float speed = forwardSpeed * Input.GetAxis("Vertical");
        playerController.SimpleMove(speed * forward);

I read online that these can be converted in blender, is that true?