From the Spring '21 release, Partner Commerce uses the Collaboration header for creating collaboration request via API and SDK integration to create quotes and orders. With this, you must select Digital Commerce from the Collaboration Type field.
With API integration, the [POST] /collaborationrequests API is used to create collaboration request. Using [POST] /collaborationrequests/:recordId/carts, a cart is generated based on the collaboration request. This method when called copies the header fields from the collaboration request to the cart.
With SDK integration, a cart is created from the UI. You can add products to the cart and then checkout.
If you have added custom fields to the Collaboration object, you must assign appropriate user permissions to the custom fields.
With this, you must also select Digital Commerce from the Collaboration Type field in your Salesforce org.
If Digital Commerce is not available as a picklist value in the Collaboration Type field, you must add it manually.
To add the picklist value:
Go to the Product Configuration object and from the Custom Fields & Relationships section, click the Collaboration Request field.
Scroll down to the Lookup Options related list and from the Related to field, click the Collaboration Request link. The Collaboration Request custom object appears.
From the Custom Fields & Relationships section, click the Collaboration Type field.
Scroll down to the Values related list and add Digital Commerce as a picklist value.