For a shopping cart/product configuration to go through the approval process, approval values must be available from the Status field.

To add values to the Status picklist

  1. From Setup, go to Create > Objects and click Product Configuration.
  2. From Custom Fields & Relationships, click Status.
  3. From Picklist Values, click New and add "Approval Required" and "Pending Approval".
  4. Click Save.

These values are now be available from the Status picklist for a Product Configuration object record, which also means the status can appear in the Status field at the top left of the shopping cart.