Hi aacmn1,
I just tested it for your renewal, and it works fine. Just select if you want to reactivate your 3 months pro subscription, or upgrade to 6 or 12 months pro. Then you then need to enter the coupon code exactly as you got it below the basket and click the "Redeem coupon" button next to it, and it gets applied to your basket.
You can private message me if you still have issues, or just reply to this thread if it now worked for you.