Hello John,
Hope you are doing well. Lately, but we have an update for you. It is not possible to have our plugin work for Free product because of WooCommerce dependency. Our plugin extends WooCommerce’s payment gateway class and by default payment gateway does not apply when a product has a zero price.
There is a hack though, you can paste this line of code to your active theme/ child theme’s functions.php file.
add_filter( ‘woocommerce_cart_needs_payment’, function($needs_payment, $cart){return true;}, 100, 2 );
This will show the Order on WhatsApp option on the checkout page, but please note that it will also show the other active payment gateways.
Best regards,
INTOLAP Support