Inventory System Using InScope Studios Tutorial Help

I have been following InScope Studios tutorial (first video, I haven't gone any farther because I can't) for creating an inventory system and here is my script:

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 public class Inventory : MonoBehaviour {
     private RectTransform inventoryRect;
     private float inventoryWidth, inventoryHeight;
 
     public int slots;
     public int rows;
     public float slotPaddingLeft, slotPaddingTop;
     public float slotSize;
     public GameObject slotPrefab;
 
     private List<GameObject> allSlots;
 
     void Start (){
         CreateInventoryLayout ();
     }
 
     void CreateInventoryLayout (){
         allSlots = new List<GameObject> ();
 
         inventoryWidth = (slots / rows) * (slotSize + slotPaddingLeft) + slotPaddingLeft;
 
         inventoryHeight = rows * (slotSize + slotPaddingTop) + slotPaddingTop;
 
         inventoryRect = GetComponent<RectTransform> ();
 
         inventoryRect.SetSizeWithCurrentAnchors(RectTransform.Axis.Horizontal, inventoryWidth);
         inventoryRect.SetSizeWithCurrentAnchors(RectTransform.Axis.Vertical, inventoryHeight);
 
         int columns = slots / rows;
 
         for(int y = 0; y < rows; y++){
             for(int x = 0; x < columns; x++){
                 GameObject newSlot = (GameObject) Instantiate(slotPrefab);
 
                 RectTransform slotRect = newSlot.GetComponent<RectTransform> ();
                 newSlot.name = "Slot";
 
                 newSlot.transform.SetParent(this.transform.parent);
 
                 slotRect.localPosition = inventoryRect.localPosition + new Vector3(slotPaddingLeft * (x + 1) + (slotSize * x), -slotPaddingTop * (y+1) - (slotSize * y));
 
                 
             }
         }
     }
 }

The result for this script is this:

The slots are outside of the canvas and not on the inventory background (The brown square at the top of the canvas). I'm not sure what isn't working. I think I copied exactly from the tutorial.

Thank you very much!