Can't get roll-a-ball behavior script (my first script) to work...

I went through all of the instructions exactly up to this point (step 9):

Roll-a-ball step 9 video tutorial

I can't get the ball to move, nor the C# variable speed to appear as a parameter in Unity editor (2 issues).

I tried setting the speed to 10.0f manually in the code, and the ball still won't move. There are no compilation or runtime errors.

My script is:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.InputSystem;
 
 public class NewBehaviourScript1 : MonoBehaviour
 {
     private float speed = 10.0f;
     private Rigidbody rb;
     private float movementX;
     private float movementY;
 
     // Start is called before the first frame update
     void Start()
     {
         rb = GetComponent<Rigidbody>();
     }
 
     void OnMove(InputValue movementValue)
     {
         Vector2 movementVector = movementValue.Get<Vector2>();
         movementX = movementVector.x;
         movementY = movementVector.y;
     }
 
     void FixedUpdate()
     {
         Vector3 movement = new Vector3(movementX, 0.0f, movementY);
         rb.AddForce(movement * speed);
     }
 }