On your index file, assign the value from composer autoload to a variable.
$autoload = require_once __DIR__ . '/vendor/autoload.php';
Use the Composer helper to pass the autoload variable, this will be used to load the configurations, routes, and other files.
eru123\helper\Composer::set_autoload($autoload);
Or if you are lazy like the creator himself to type all that namespacing, you can use the set_autoload
function directly.
set_autoload($autoload);
Or if you are still surprisingly lazy, you can just (go fuck and die, just kidding we're all holy ones here) require the autoloader and it will do it itself when it's needed.
require_once __DIR__ . '/vendor/autoload.php';