post https://..com.br/api/fulfillment/pvt/orders//fulfill
Creates fulfillment order, meaning that it is an order for the seller's side in a sale made through a marketplace. This order assumes the transaction itself has already happened on the marketplace's side and, therfore, cares only about the fulfillment side.
For a detailed explanation of the steps required to develop a custom connector to become an external marketplace for VTEX sellers, check out our complete External Marketplace Integration Guide.