How to get a pizza for free from Pizza Pizza?

From April 17, 2017 through June 18, 2017, spend $9.99 or more (before taxes and delivery) at, or through Pizza Pizza’s apps using Visa Checkout,
excluding the Pizza Pizza iPad app (the “Eligible Pizza Pizza Apps”) , and receive one (1) unique voucher code valid towards a free small cheese or pepperoni pizza with your next online order, until quantities last. Limit one (1) voucher code per transaction regardless of the size of purchase.
View details here