Use the same Google account that received the invitation. Remove any old USB-installed build before installing from Google Play.
Join the test and install from Google Play
- Open the Play invitation with the Google account that should become a tester.
- Accept the invitation and wait until Google Play marks you as a tester.
- Install or update the app only from Google Play. Do not keep an old APK installed from USB or file manager.
- If the page says you are already a tester, continue to the Play Store listing and install the current test build.