Will this work with variable products? Also, is it possible to share the whole code because I did not get this part. "then used woocommerce_process_product_meta_simple to save the data. And then by using woocommerce_add_cart_item_data, woocommerce_before_calculate_totals actions, I added the cart meta into it for the custom field i just created and set the item price to zero so user can be able to checkout with zero pricing."

Thanks for offering help!