Hi. Can you give us more information about what settings you use in your UE project, Build settings, gradle version…
I already did all theses steps multiple times and have been facing the same errors in version 5.3.2 and 5.4.2/5.4.4
The only UE projects that worked correctly for me in the Play Store were made with version 4.27
Other people are having the same errors in versions 5+ like Google Play Services / Show External Login UI / In-App Purchases / Play Integrity
People with the errors:
(Most important things to publish android game is broken. Login & in-app Purchase Don't work in all version.)
(Android In App Purchase)
([Android][UE 5.3] Start an In-App Purchase Crash (w/ Callstack))
(When switching to target API 34 Google Play Login window does not show up anymore UE 5.3.2)
(Google Play Services Show External Login UI node NEVER fires OnSuccess)