Why would you have needed to add anything more to your order to get free shipping? Your message indicates that you are a member, and members get free shipping with no minimum purchase requirement. Unless Criterions are excluded, but that seems unlikely.
If the member discount policy has been changed, they need to update the Terms and Conditions online, last updated 10/16/2019, where it says in section 2: "b) The Everyday Member Discount is only valid on eligible purchases at any Barnes & Noble Store. The Everyday Member Discount is not...