Known issue and fix for iPhone6S and early iPads.
Only early Apple devices there is a bug where, upon App installation, a user is promoted with "Realar" Would Like to Access the Camera. The Camera is required to show AR places so if either the user isn't prompted; or a user selects Don't Allow, this then causes the App to function improperly (failing to render screen graphics).
In either case, this problem can be resolved by user You can turn Camera Settings on or off at Settings > Privacy > Privacy and toggle Realar to "on" and Restart the Realar App. For more information About privacy and Location Services in iOS 8 and later go to https://support.apple.com/en-au/ht203033.