How to test In App Purchases on TestFlight

I need help to set up App Store Connect, Unity IAP settings and test on TestFlight.

In app purchases are working in Unity project and the game is published Google play store.

After submitting game to Apple review, it failed on IAP because checkout button not working.

After pushing game to TestFlight, the checkout button not connecting to in app purchases and purchases can’t be completed. I’m stuck with setting up Dashboard for iOS IAP, I need that someone connect with andydesk and help me to set up dashboards.

Required : Anydesk – to check project before start work.