Ensure your Google Play Services is updated to at least v26.13.32 to keep apps running. How to Install the APK on Android 5.1.1
: To keep the store functional, you may need the last supported Play Services version (v24.28 or lower). Later versions like v26.13.32 are available but are designed for Android 6.0 and above. Android API Levels Step-by-Step Installation Guide