Retrieve an order by its ID, including associated customers, payments, pay schedule, and invoice send history. An order is a record linking one or more payments to a service or product. Orders can be one of three types:

• Unscheduled: A simple order with no pay schedule (one-time invoice).
• Payment Plan: An order with a pay schedule and a total amount. A fixed minimum amount is due each period. Extra payments can be made at any time. The plan ends once the total amount is paid in full.
• Subscription: An order with a pay schedule but no total amount. A fixed amount is due each period indefinitely until cancelled.