Question Why are the assets not being loaded?

I am a beginner in c# so please excuse my lack of knowledge.
I am trying to add the asset to scene through a button that has all of these scripts but nothing happens when I press the button. What am I missing?

Add Model Script?

Code (CSharp):

1. using System.Collections.Generic;
2. using UnityEngine;
3. using UnityEngine.XR.ARSubsystems;
4. using UnityEngine.XR.ARFoundation;
5. using UnityEngine.EventSystems;
6. using UnityEngine.UI;
7.  
8. public class AddModel : ContentController
9. {
10.     public ARRaycastManager raycastManager;
11.     public GraphicRaycaster raycaster;
12.     public ContentController contentController;
13.  
14.     public void Start()
15.     {
16.         contentController.LoadContent(name);
17.     }
18.  
19.     private void Update() {
20.  
21.         if (Input.GetMouseButtonDown(0) && !IsClickOverUI()) {
22.      
23.             List<ARRaycastHit> hitPoints = new List<ARRaycastHit>();
24.             raycastManager.Raycast(Input.mousePosition, hitPoints, TrackableType.Planes);
25.  
26.             if (hitPoints.Count > 0) {
27.                 Pose pose = hitPoints[0].pose;
28.                 transform.rotation = pose.rotation;
29.                 transform.position = pose.position;
30.             }
31.         }
32.     }
33.  
34.     bool IsClickOverUI() {
35.         //dont place content if pointer is over ui element
36.         PointerEventData data = new PointerEventData(EventSystem.current) {
37.             position = Input.mousePosition
38.         };
39.         List<RaycastResult> results = new List<RaycastResult>();
40.         raycaster.Raycast(data, results);
41.         return results.Count > 0;
42.     }
43. }
44.  

Content Controller script

Code (CSharp):

1. using System;
2. using UnityEngine;
3.  
4. public class ContentController : MonoBehaviour
5. {
6.     public API api;
7.     public void LoadContent(string name) {
8.         DestroyAllChildren();
9.         api.GetBundleObject(name, OnContentLoaded, transform);
10.     }
11.  
12.     public void OnContentLoaded(GameObject content) {
13.         //do something cool here
14.         Debug.Log("Loaded: " + content.name);
15.     }
16.  
17.     void DestroyAllChildren() {
18.         foreach (Transform child in transform) {
19.             Destroy(child.gameObject);
20.         }
21.     }
22.  
23. }
24.  

API script

Code (CSharp):

1. using System.Collections;
2. using UnityEngine;
3. using UnityEngine.Events;
4. using UnityEngine.Networking;
5.  
6. public class API : MonoBehaviour
7. {
8.     const string BundleFolder = "http://fyp-coursework.freecluster.eu/AssetBundles/";
9.  
10.     public void GetBundleObject(string assetName, UnityAction<GameObject> callback, Transform bundleParent) {
11.         StartCoroutine(GetDisplayBundleRoutine(assetName, callback, bundleParent));
12.     }
13.  
14.     IEnumerator GetDisplayBundleRoutine(string assetName, UnityAction<GameObject> callback, Transform bundleParent) {
15.  
16.         string bundleURL = BundleFolder + assetName + "-";
17.  
18.         //append platform to asset bundle name
19. #if UNITY_ANDROID
20.         bundleURL += "Android";
21. #else
22.         bundleURL += "IOS";
23. #endif
24.  
25.         Debug.Log("Requesting bundle at " + bundleURL);
26.  
27.         //request asset bundle
28.         UnityWebRequest www = UnityWebRequestAssetBundle.GetAssetBundle(bundleURL);
29.         yield return www.SendWebRequest();
30.  
31.         if (www.result != UnityWebRequest.Result.Success) {
32.             Debug.Log("Network error");
33.         } else {
34.             AssetBundle bundle = DownloadHandlerAssetBundle.GetContent(www);
35.             if (bundle != null) {
36.                 string rootAssetPath = bundle.GetAllAssetNames()[0];
37.                 GameObject arObject = Instantiate(bundle.LoadAsset(rootAssetPath) as GameObject,bundleParent);
38.                 bundle.Unload(false);
39.                 callback(arObject);
40.             } else {
41.                 Debug.Log("Not a valid asset bundle");
42.             }
43.         }
44.     }
45. }
46.