Activate free shipping for regular customers

add_filter('woocommerce_shipping_free_shipping_threshold', 'free_shipping_for_returning_customers');
function free_shipping_for_returning_customers($threshold) {
    if (is_user_logged_in() && current_user_can('customer_group')) {
        $threshold = 0; // Versandkostenfrei für Stammkunden
    }
    return $threshold;
}