To let the customer know that you have completed an order, click Submit a Delivery on the order page. This button is available only if the order has In Progress or Revision Requested statuses.
If the customer approved the delivery, then the order will be marked as Order Complete. If the customer is not satisfied with the delivery, they can request a revision. In this case, your delivery will be declined, and the order status will be changed to Revision Requested.
Note: You should submit a delivery for all kinds of services.