"The device or user is not allowed to make the purchase" error

This error could be due to a few reasons. Try the following troubleshooting steps:

1. Make sure your device/emulator is completely updated.
2. Try running on device. Sometimes the emulator glitches out and it must be restarted. Overall, testing on device is more reliable.
3. Restart your device/emulator.
4. Make sure you're logged in with a Google account.
5. If you're running on an emulator, make sure it has Google Play installed.