Why doesn’t Good On You data match with my Google Analytics data?

It may be because Google Analytics attributes conversions using a different model to Good On You, 

Good On You uses a last-click attribution model. The affiliate tracking system attributes a conversion when a sale occurs within 30 days of a user clicking on a tracking link, on the same device. That means you pay commission on sales where the user was referred by Good On You and they come back up to 30 days after to complete a purchase. However, only if that purchase was completed on the same device they used when they initially clicked the tracking link.

Google Analytics is also not able to track data on clicks and conversions referred via our Publishers.