Over the years, Facebook (and Meta) has updated the app to require:
The version you installed is too new for Android 2.1. Solution: Uninstall and try an older version. Look for Facebook version 12.0.0.0.10 or lower. download facebook app for android 2.1
Today, you cannot download a working, officially supported Facebook app for Android 2.1 from the Google Play Store, because: Over the years, Facebook (and Meta) has updated
Open the default browser and type mbasic.facebook.com . Over the years
Because Android 2.1 (API Level 7) is extremely old, you must use specific legacy versions released between 2011 and 2014. Newer versions will fail to install or crash immediately.