A pop-up will ask: "Do you want to download the last compatible version?" Select Download . 2. Sideloading via Facebook IPA File
Downloading and installing the Facebook app on iOS 9.3.5 is a common challenge for owners of legacy devices like the iPad 2, iPad Mini 1, or iPhone 4S. Because these devices are built on 32-bit architecture and the modern App Store requires 64-bit hardware, you cannot simply "get" the latest version.