If you want, I can:
Cause: The APK is corrupted or incompatible (e.g., x86 version on ARM device).
Fix: Re-download the ARM version from APKMirror. For 2012–2015 devices, choose armeabi-v7a or arm64-v8a depending on your CPU.
Cause: Google Play Services is too old or missing. Gmail relies heavily on Play Services for authentication and push notifications.
Fix:
If the user proceeds, the typical installation path is:
Note: The user will not receive future updates for this app via the Play Store.