How do I notify Affiliates Plugin that a referral has paid and to credit referrer?

Unfortunately, I’m to far into a custom membership site to turn back but I’d like to use Affiliate for users to refer.

My question is, everything is fine – I can track the referral with the referrer’s ID through checkout and to the congrats page. Even writing the data to users account.

I have a place to hook after payment where I can notify other scripts/apps.

What I can’t seem to find is how to use the notification hook to notify Affiliates Plugin to credit a user.