Yes, you need to also add the store order details behavior to the confirm page.
In the store order details behavior, when you select the ID column, it is not asking for the Primary Key "DetailsID" column. It is asking for the columns that creates the order -> OrderDetails Relation ship, the "DetailsOrderId" column.
before adding the store order details behavior, go back into the Store Order summary Behavior and look at the Session Variable section.
In this section, the OrderID column should be selected as the ID Column, and make not of the name of the session variable that will be created.
When the order is stored in the database, the value of the OrderID column will be stored in this session variable.
In the store order details behavior, set the ID column to use the DetailsOrderID, with the details Order ID columns selected, click the lightning bolt next to value and expand the Session Collection, find the session variable created by the Store order summary behavior and select it.