Checkout Payments API request types and payment tokens
Key Takeaway
Match paymentToken to requestType: a card payment method ID for Auth, the provider's transaction identifier for PostAuth, and the purchase order number for SimplePurchaseOrder.
The Checkout Payments API is the Connect REST resource a Commerce store uses to attach a payment to a checkout so an order can be placed. Each request names a requestType. The paymentToken value means something different for each type, so the core skill is knowing which token goes with which type.
Calling the resource
To place an order, you submit a tokenized payment from a payment provider through the Checkout Payments API. The same resource works for Salesforce Payments and for custom payment adapters.
The endpoint is available from API version 55.0: POST /commerce/webstores/{webstoreId}/checkouts/{activeOrCheckoutId}/payments. For activeOrCheckoutId, pass either the checkout ID or the value active to target the active checkout. In XML, the request body's root tag is <checkoutPaymentInput>.
Calling the resource requires a B2B or D2C Commerce license. You also need the system permissions in the "Buyer" preconfigured permission set (B2B stores only) or the "Shopper" preconfigured permission set (D2C stores only).