Time for a new device. Apple dropped support in iOS 11 for anything without a 64-bit processor. Effectively, anything from an iPhone 5 / 5C and older, and for the iPad, anything from the iPad 4 and older.
If your device is newer than the models mentioned above, Settings > General > Software Update. Keep checking until the software is up to date, and this should fix the problem.
And the issue is?
using apps on Apple devices require the iOS be compatible with the apps
