This is the most critical detail to understand:
You cannot simply "open" an IPA file on an iPhone. You will need a tool like Sideloadly or AltStore to install it from a computer. facebook old version ipa
If you are trying to get Facebook working on a specific old device, I can help you find the you need. Could you tell me: What model of iPhone or iPad are you using? Which iOS version is it currently running? This is the most critical detail to understand: