How to setup post purchase upsell?

You should read this to understand what is post-purchase upsell and its benefits:

1) Click on post purchase upsells from AMP Dashboard

2) Make sure you have selected AMP Conversion as your post-purchase app. You can do that by clicking at the button showed below

3) Once you have done that, you can activate part upsell title and CTA buttons. Finally, pick the upsells and discount you want from Rules page:

4) Come back to Post Purchase upsells page, if everything looks okay - SAVE the page and we recommend you place a test order to confirm