If the IPA requires iOS 6 or above, it will refuse to install. Additionally, if the binary inside the .app is 64-bit (ARM64) only, the 32-bit ARMv7 kernel of iOS 5.1.1 cannot execute it.
To actually use these files today, you typically need to follow these steps: ipa ios 5.1.1
Since the official App Store no longer supports many iOS 5 apps, you’ll need to rely on community archives. If the IPA requires iOS 6 or above,