Register Another Stylesheet for MemberPress Courses Add-on With a Child Theme

Hey everyone,
I am using a child theme for Twenty Twenty One, the MemberPress Courses Add-on, and I am trying to register and enqueue a stylesheet for that Add-on.

This is how I registered and enqueued this new stylesheet

// Stylesheet for MemberPress Classroom
function ly_register_classroom_style(){
    wp_register_style( 'ly-classroom-style', get_stylesheet_directory_uri() . 'assets/css/ly-memberpress-style.css' );
    wp_enqueue_style( 'ly-classroom-style',
        get_stylesheet_directory_uri() . 'assets/css/ly-memberpress-style.css',
        array( 'child-style' ),
        wp_get_theme()->get('Version')           
                    );
}
add_action( 'wp_enqueue_scripts', 'ly_register_classroom_style' );

And this is the filter I added below, provided by MemberPress support

add_filter('mpcs_classroom_style_handles', 
    function($allowed_handles){
        $allowed_handles[] = 'ly-classroom-style';
    return $allowed_handles;
}
          );

It’s not working…
What am I missing? What am I doing wrong?
Thank you so much in advanced!

PS: If I add the CSS in the customizer, my style is applied. But I wrote so many lines that I’d like to have this on a separate stylesheet

The page I need help with: [log in to see the link]