Wordpress spl_autoload_register not working with wordpress

Question

So i'm making a wordpress website where I want to migrate my wordpress website to an online hosting platform. I did that with the all-in-one Wp Migration plugin, but i got a critical error message.

I fixed it and looked in the directadmin panel for apache errors. The problem is the custom theme I am making. I'm using an spl_autoload_register function from php and it gives the following error in directadmin:

Backend fatal error: PHP Fatal error: Uncaught Error: Class 'Website\Backend' not found in

The code i'm using for my autoload function is this:
File: functions.php

include __DIR__ . '/autoloader.php' ;
$backend = new Website\Backend();

File: autoloader.php

spl_autoload_register(function($className) {
    $className = ltrim($className, '\\');
    $className = str_replace(__NAMESPACE__, '', $className);

    $path = __DIR__ . '/classes/' . str_replace('\\', '/', $className) . ".class.php";
    if(file_exists($path)) {
        include $path;
    }
    return;
});

file: backend.php

    namespace Website;
    class Backend 
    {    

    }

folderstructure:

• classes/
  • website/
    • backend.class.php
• functions.php
• index.php

Works on local server but not on hosting Anything doing wrong here?