Just notice that when doing any app or in-app purchase on Android TV device, there's new 'Complete your purchase on another device' screen will appear if choose 'More payment options' or if your Google Play has insufficient balance to complete the purchase.

There will be two option to complete the purchase:

1. It will automatically send notification to your android device that is linked to the same Google account as your Android TV.
   The notifications also can be access on Google Playstore app > Offers & notifications section.
2. On web browser, go to 'g.co/PlayContinue' and then it will redirect to 'play.google.com/store/devicehandoff' .

Pictures: https://imgur.com/a/zHFac47