If you want to recognize which affiliate referred the sale according to the coupon code which was used during the purchase, then this is a theoretical overview of how it should be integrated.
In order to make this work, you have to use the same coupons in your payment processor (or e-shop) as in your Post Affiliate Pro. Basically, you should generate coupons in Post Affiliate Pro and then import these coupons into your payment processor or generate coupons in your payment processor and then import them into Post Affiliate Pro - do whatever is easier for you.
Then you need to edit the sale tracking code that is fired in your thank you page and add this line of code
- in the HTML pixel: &Coupon=Coupon_Code
- in the php API sale tracking code: $sale->setCouponCode('Coupon_Code');
Instead of 'CouponCode' you should use the variable that holds the actual coupon code which was applied to the order. Provider/creator of your payment processor/eshop should know the names of all the variables used and help you with this.
You can also sent multiple coupon codes separated by comma if your solution allows multiple coupon codes to be applied to an order. The first coupon associated with an affiliate in Post Affiliate Pro will be taken into account.
The actual tracking process will look like this: the client will purchase something and he will use the coupon code during the purchase (your coupon has discount for example 10% - set in your payment processor). When the client pays for the order, he is sent to the thank you page which will read the variable of the coupon and insert the exact coupon code that has been used into the sale tracking code. This script will be fired and everything necessary will be sent to Post Affiliate Pro including the coupon code and then the system will recognize which affiliate referred this client based on the coupon code.