When the customer clicks a button to submit the order, the Store API createOrder endpoint is called. The request includes a parameter ("op":"complete") to specify that a previously initiated order is being completed. The request must also include the order ID and the payment group ID.

The server invokes the Generic Payment webhook, which sends an authorization transaction request to the checkout system. Any custom properties in the order are included in the webhook request. The webhook response should indicate whether the authorization succeeded. If the authorization succeeds, the order is submitted and the shopper is redirected to the Order Confirmation page.