There are legitimate reasons to want an older version of the Facebook app—perhaps you preferred the user interface, or your current phone is struggling with the resource-heavy modern version. Because official app stores (Google Play, Apple App Store) only offer the latest version, you must use "sideloading" for Android or specific workarounds for iOS.
Before you can install an old version, you must prepare your Android device. Note that this process is generally not possible on iOS (iPhone) without jailbreaking, as Apple does not allow "side-loading" apps. download the old version of facebook
Recommendation: Use APKMirror, as they verify that the files have not been tampered with. There are legitimate reasons to want an older
