Fortunately, you can still install a working, compatible version of Facebook on your legacy iOS device. This guide covers the safest and most reliable methods to get Facebook running on iOS 12.5.5. Method 1: The "Purchased" Section Trick (Easiest)
Installing an older version of Facebook on iOS 12.5.5 can be challenging because:
If you have never downloaded Facebook on your Apple ID, it won't appear in your "Purchased" list.
Facebook frequently updates its authentication protocols. An old app may not support modern login methods, potentially leaving you unable to access your account at all.