Create Order Package Fulfillment is a special endpoint used to create fulfillments for an order that require separate packages. In the example, you can see two packages for the same order. Each package can contain more than one product — just include the id and quantity of each item within the corresponding items array.
For shipments that will only use one package, use the standard POST fulfillment request instead.
"logisticMode": "seller-Ecommerce" is required if you're using the fulfillment creation request where you will generate the shipping label (i.e., third-party shipping, not handled by Temu).
To obtain the "companyId", you'll need to make a request to Get Carriers.
items.id corresponds to the product ID within the order. Both the ID and the quantities must match the information in the order.