Add custom custom role to new members - WebToffee WooCommerce Memberships

functions.php

add_filter('hf_memberships_new_membership_data', 'webtoffee_assign_role_after_membership');

function webtoffee_assign_role_after_membership($new_membership_data, $user_id_product_id_order_id) {

    $theUser = new WP_User($user_id_product_id_order_id['user_id']);
    
    $role = 'mycustomrole'; // string $role = Role name 
    
    $theUser->add_role($role);

    return $new_membership_data;
}

// https://wordpress.org/plugins/xa-woocommerce-memberships/