Steambirds: Survival cannot be installed on iOS 11 and higher devices

Unfortunately that is correct. Compatibility with iOS 11 required developers to make certain upgrades to older apps including Steambirds: Survival. We have stopped work on Steambirds: Survival and will probably not be able to address this issue. The app should still (mostly) work with older versions of iOS if you have a device still running iOS 10 or lower.