Initially you could get discounts with your AAA card alone at all the restaurants and shops at CityWalk, IOA and Universal. Then the policy changed a couple of years ago.
After the policy change you could no longer get discounts in the Wizarding World. You could get discounts at restaurants in the other areas of the parks and CityWalk by just showing your AAA card, but you needed that printed voucher to get the discounts on merchandise along with showing your AAA card at the shops.
Your local AAA office should be able to print you one. They should have included it in your ticket package unless they have another arrangement with Universal.
You can take your paper tickets from AAA to guest services and exchange them for the small ticket cards to put in your lanyard. So much easier to deal with.
What I did a few years ago to get the most bang for my buck is I looked around for all the gifts I wanted to purchase then purchased them at the big Islands of Adventure Trading store just inside IOA or the Universal store at CityWalk.
You had to spend $50.00 to get 10% off with the AAA CARD and voucher, then once you got to $75.00 you saved 15%.