Hook in and alter the waitlist button URL if your website structure is different to the standard
/**
* Alter the WooCommerce Waitlist Button URL
*/
add_filter( 'wcwl_toggle_waitlist_url', 'customise_waitlist_toggle_url', 10, 2 );
function customise_waitlist_toggle_url( $url, $product_id ) {
return str_replace( home_url(), home_url( 'custom-directory' ), $url );
}