Load .fbx from remote http server at runtime to use it as animation clip at runtime

I would like to implement a WebGL application where animationclips will be downloaded from an http remote server and loaded to a 3D model's AnimatorController at runtime. For example, the following code shows that the user can type a url to the input field and when they press the "Submit" button, the system should go connect and login to the server, and then download the fbx which will be used as animationClip for the 3dmodel:

 using System;
 using System.Collections;
 using UnityEngine.UI;
 using UnityEngine;
 using UnityEditor.Animations;
 using System.Net;
 
     public class DownloadAsset : MonoBehaviour{
            
         public InputField nameField;
         string url;   //the url that contains the path of my animation clip (fbx) to be donwloaded or streamed
 
         public AnimatorController AnimationController; //the animatorController of my 3d model
         public AnimationClip AnimationClip;   
         
         public void OnSubmit(){
                   url = nameField.text;
                   WebClient myClient = new WebClient();
                   myClient.Credentials = new NetworkCredential( username, password );
                   myClient.DownloadFile ( url, "C:/Users/myusername/Desktop" );
                   //Somehow I load my donwloaded or streamed asset to a variable of type AnimationClip and load it to the AnimatorController of my 3dmodel
 
                   Motion motion = (Motion)animationClip as Motion;
                   animationController.AddMotion(motion);
         }
     }

1. How can I save the downloaded fbx to a buffer and then load it to unity?

2. In this code I am using using UnityEditor.Animations which means that I will have problems when building the app.How should I alternatively use functions for animations to add an animationclip to a animatorcontroller at runtime?

Please note that I will build it as WebGL app and everything has to be done at runtime.

Thank you for your patience!