post https://api-test.maast.com/platform/subscription
Creates a new subscription with a specific start date, subscribing a customer to a recurring plan or a one-off off-plan. Returns a unique subscription_id, which you can use to interact with this subscription through the API.
When the subscription includes a one-time fee, a Payment Gateway sale request is made immediately to bill the customer the one-time fee. The subscription remains active even if the request for the one-time fee fails.
Create an off-plan subscription by excluding plan_code from the request and sending the applicable fields.