Question Script has no Raycast Manager variable

I am new to Unity and have no coding experience.

I am following this AR manual: https://learn.unity.com/tutorial/placing-and-manipulating-objects-in-ar#

I am stuck on step 13:
Drag the SpawnableObject Prefab from the Project window into the Spawnable Prefab variable (figure 12)


I don't have the 'Raycast Manager' and 'Spawnable Prefab' variables in my Inspector window under the Spawnable Manager (script).

This is the code in the file:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using unityengine.xr.arfoundation;
5.  
6. public class SpawnableManager : MonoBehaviour
7. {
8.     [SerializeField]
9.     ARRaycastManager m_RaycastManager;
10.     List<ARRaycastHit> m_Hits = new List<ARRaycastHit>();
11.     [SerializeField]
12.     GameObject spawnablePrefab;
13.    
14.     Camera arCam;
15.     GameObject spawnedObject;
16.  
17.     // Start is called before the first frame update
18.     void Start()
19.     {
20.         spawnedObject = null;
21.         arCam = GameObject.Find("AR Camera").GetComponent<Camera>();
22.     }
23.  
24.     // Update is called once per frame
25.     void Update()
26.     {
27.         if (Input.touchCount == 0)
28.             return;
29.  
30.     RaycastHit hit;
31.     Ray ray = arCam.ScreenPointToRay(Input.GetTouch(0).position);
32.         if (m_RaycastManager.Raycast(Input.GetTouch(0).position, m_Hits))
33.     {
34.             if(Input.GetTouch(0).phase == TouchPhase.Began && spawnedObject == null)
35.             {
36.             if (Physics.(ray, out hit))
37.             {
38.  
39.                 if (hit.collider.gameObject.tag == "Spawnable")
40.                 {
41.                 spawnedObject = hit.collider.gameObject;
42.             }
43.             else
44.             {
45.                 SpawnPrefab(m_Hits[0].pose.position);
46.             }
47.             }
48.         }
49.         else if(Input.GetTouch(0).phase == TouchPhase.Moved && spawnedObject != null)
50.          {
51.             spawnedObject.transform.position = m_Hits[0].pose.position;
52.         }
53.         if(Input.GetTouch(0).phase == TouchPhase.Ended)
54.         {
55.             spawnedObject = null;
56.             }
57.     }
58.     }
59.    
60.     private void SpawnPrefab(Vector3 spawnPosition)
61.     {
62.     spawnedObject = Instantiate(spawnablePrefab, spawnPosition, Quaternion.identity);
63.     }
64. }
65.