Important upfront: Android 2.1 (Eclair) is very old (released 2010). Current Facebook app versions require much newer Android releases, so you cannot install the modern Facebook app from the Google Play Store on Android 2.1. Below are practical options and constraints.
.apk file to the “Downloads” folder on your phone’s SD card or internal storage.The most reliable way to access Facebook on a device this old is via its mobile website Facebook 2.1 (arm + arm-v7a) (nodpi) (Android 2.2+) download facebook app for android 2.1
: Older devices often lack the updated security certificates required to communicate with Facebook's current servers, frequently leading to "Connection Error" or login failures even if an app is successfully side-loaded. Recommended Alternatives How to download the Facebook app for Android 2