Laravel - dropbox driver - This driver does not support retrieving URLs - dropbox

Question

Using
Laravel 5.7
I'm trying to use dropbox driver to upload images , it works .. but when i want to get the url .. it gives me an error
This driver does not support retrieving URLs
filesystems.php
'disks' => [
'dropbox' => [
'driver' => 'dropbox',
'app_secret' => env('DROPBOX_APP_SECRET'),
'token' => env('DROPBOX_TOKEN'),
],
],
UploadController.php
public function postUpload(Request $request)
{
$user = Auth::user();
$file = $request->file('picture');
$filename=uniqid($user->id."_").".".$file->getClientOriginalExtension();
Storage::disk('dropbox')->put($filename, File::get($file), 'public');
$url = Storage::disk('dropbox')->url($filename);
$user->profile_pic = $url;
$user->save();
$user->profile_pic = $filename;
$user->save();
return view('upload-complete')->with('filename', $filename)->with('url',$url);
}
upload-complete.blade.php
#extends('template')
#section('content')
<div class="container">
<h1>File Uploaded</h1>
<hr />
<div class="text-center">
<img src="{{ $url }}" class="img-rounded" />
</div>
</div>
#endsection