No codes needed.
Discounts and promos apply automatically in your cart if/when criteria are met.
Also, when active, a promo is automatic based on order total value; a step during the check-out process will be offered to pick bonus items.
You may choose either the cart discounts or the promo, not both; if you pick free bonus items then you do not get the cart discounts.
However, if you prefer the cart discounts, then simply skip the promo/bonus step (do not select any bonus items) and you will keep whatever cart discounts you had for the order.
All is automatic in on the Basicstero site.