Downloading a "verified" Facebook IPA from third-party sites for iOS 9.3.5 is not recommended
Downloading a verified Facebook IPA file for iOS 9.3.5 can be a bit tricky, but by following the steps outlined in this write-up, you should be able to successfully download and install the app on your iOS device. Remember to always use a trusted source and verify the file before downloading it.
On your iOS 9.3.5 device, go to the App Store . Go to "Purchased": Tap the "Purchased" tab at the bottom.
A prompt will appear: "Download an older version of this app?" Tap Download .