If you are stuck on iOS 12 or 13, the official App Store will only let you download the "last compatible version." However, sometimes even that fails. A user might look for an older IPA (version 2.12.7, etc.) to manually install via a computer.
An .ipa file is the format used for iOS applications. When people search for terms like "ipa apps.me whatsapp," they are usually looking for one of two things: ipa apps.me whatsapp