The Pay Online button is a feature in the Quote for draft orders template in the Order Printer Pro app that allows your customers to pay for their draft orders. It's a straightforward and secure process that can help you streamline your payment processing and make it more efficient for your customers.

The Pay Online button is designed to work with the draft orders feature built into Shopify. It uses the {{ invoice_url }} Shopify variable, which inserts a link your customers can follow to pay for the invoice using Shopify's secure checkout. This variable allows you to link the button with the unpaid order.

While the Pay Online button is a useful feature, it's worth noting that the {{ invoice_url }} variable used to redirect customers to the payment page only works for draft/non-completed orders. Once you complete the order, it will convert to a regular order, and the link will redirect to the actual template instead of the checkout to pay for the order.

For example, this order is completed. Therefore, the Pay Online button on the Quote for draft orders is expected not to redirect you to the payment page.

The reason or nature of this behavior is defined by Shopify itself, as they determine what the variable does. Unfortunately, we can't control the link's behavior. For more information about the Draft Order Properties, you may check the Shopify article.

If you need to create a link for a regular order, you may use the {{ order_status_url }} variable instead. This variable will redirect customers to the order status page, where they can pay for their order using the 'Pay Now' button.

Once set up, you can get in touch with Shopify support so they can give you guidance on how to allow your customers to pay directly from the order status page, in case you and your customers don't see this option there.