Follow the below steps to redeem your promo code:
1) Select the "Start Free Trial" button OR select a subscription plan here to sign-up for a Stage Access subscription.
2) Before you proceed to Create Account/Password for your new subscription, look for "Have a Promo Code? Add" and click on "Add" to enter your code.
You can also enter the promo code on the Add Billing information section that appears below your First Payment amount details. Look for "No Code Applied. Edit" and click on "Edit" to enter your code.