How to fix a bug in Quaternion code in Unity 2.4.5?

Question

C++ / C#

How to fix a bug in Quaternion code in Unity 2.4.5?
I made code to make the character walk.
Wrote the code "Move":

using UnityEngine;

[RequireComponent (typeof(Rigidbody))]
public class go : MonoBehaviour 
{
    private Camera cam;
    private Rigidbody rb;

    private Vector3 velocity = Vector3.zero;
    private Vector3 rotation = Vector3.zero;
    private Vector3 rotationCamera = Vector3.zero;

    void Start() 
    {
        rb = GetComponent <Rigidbody> ();
        cam = Camera.main;
    }

    public void Move (Vector3 _velocity)
    {
        velocity = _velocity;
    }

    public void Rotate(Vector3 _rotation)
    {
        rotation = _rotation;
    }

    public void RotateCam(Vector3 _rotationCam)
    {
        rotationCamera = _rotationCam;
    }

    void FixedUpdate()
    {
        PerformMove();
        PerformRotate();
    }

    void PerformMove()
    {
       if (velocity != Vector3.zero)
       {
            rb.MovePosition(rb.position + velocity * Time.fixedDeltaTime);
       } 
    }

    void PerformRotate() {
        rb.MoveRotation (rb.rotation + Quaternion.Euler (rotation));
        if (cam != null) {
            cam.transform.Rotate(-rotationCamera);
        }
    }
}

And looking for one "Control":

using UnityEngine;

[RequireComponent(typeof(go))]
public class control : MonoBehaviour {

    [SerializeField]
    private float speed = 5f;
    [SerializeField]
    private float lookspeed = 3f;
    private go motor;

    void Start()
    {
        motor = GetComponent<go>();
    } 

    void Update() {
        float xMov = Input.GetAxisRaw("Horizontal");
        float zMov = Input.GetAxisRaw("Vertical");
        Vector3 movHor = transform.right * xMov;
        Vector3 movVer = transform.forward * zMov;

        Vector3 velocity = (movHor * movVer).normalized * speed;

        motor.Move(velocity);
        float yRot = Input.GetAxis ("Mouse X");

        Vector3 rotation = new Vector3 (of, yRot, of) * lookspeed;
        motor.Rotate(rotation);

        float xRot = Input.GetAxis ("Mouse Y");

        Vector3 camrotation = new Vector3 (xRot, of, of) * lookpeed;

        motor.Rotatecam(cam_rotation);
    }
}

Added to the object, launched.
Error: Operator '+' cannot be applied to operands of type 'Quaternion' and 'Quaternion'.
How to fix?

Answer 1

For what you need, there must be a method. look at the appropriate ones in
https://poqxert.ru/blog/unity/tutorials/matematika...

Answer 2

Perhaps in this version of the unit, not everything is so smooth. Install 2019 or 2020 version and try it.