Can’t download the app? Then you may need to update the Android /iOS version (software) on your mobile device, under Settings.
Can’t download the app even though you have updated? Then your mobile device is probably out of date and not compatible with the app.
Technical explanation! For iOS, the app works if you have the latest operating system or one of the two previous versions. For Android, the app works if you have the latest operating systems or one of the three previous versions.