Why won't this jump code work?

I've been following this tutorial on making a character controller and I'm trying to get the player to jump but only when it's grounded. Here is the code.

 public class WalkingController : Controller
 {
     //Movement information
     Vector3 walkVelocity;
     Vector3 previousWalkVeloctiy;
     float adjVertVelocity;
     float jumpPressTime;
 
 
     //Setting
     public float walkSpeed;
     public float jumpSpeed;
 
 
     public override void ReadInput(InputData data)
     {
         previousWalkVeloctiy = walkVelocity;
         ResetValues();
 
         //set horizontal movement.
         if(data.axes[0] != 0f)
         {
             walkVelocity += Vector3.right * data.axes[0] * walkSpeed;
         }
 
         //set jump movement.
         if (data.buttons[0] == true)
         {
             if (jumpPressTime == 0f)
             {
                 if (Grounded())
                 {
                     adjVertVelocity = jumpSpeed;
                 }
             }
             jumpPressTime += Time.deltaTime;
         }
         else
         {
             jumpPressTime = 0f;
         }
 
 
         newInput = true;
     }
 
     //method that looks below the player to see if something is there.
     bool Grounded()
     {
         return Physics.Raycast(transform.position, Vector3.down, coll.bounds.extents.y + 0.1f);
     }
 
     void ResetValues()
     {
         walkVelocity = Vector3.zero;
         adjVertVelocity = 0f;
     }
 
     void LateUpdate()
     {
         if (!newInput)
         {
             previousWalkVeloctiy = walkVelocity;
             ResetValues();
             jumpPressTime = 0f;
         }
 
         /*
          * FYI:
          * Here we set the Vectors to the velocity of the rigidbody. Setting the Y value of
          * the new Vector2 Means that the player will fall down normally. If set to 0 it would
          * either keep the player from falling or make them fall very slowly.
          */
         rb.velocity = new Vector3(walkVelocity.x, rb.velocity.y + adjVertVelocity);
         newInput = false;
     }
 
 }

The tutorial is more designed for a 3d game, and I put this character controller on a cube just to see what would happen and it worked fine. I'm not sure why it wouldn't work on a 2D sprite as well. I even tried changing the raycast to be a 2D raycast, but that didn't work to well because Raycast2D isn't a bool like Physics.Raycast is. Any explaination would be greatly appreciated! :D