You can use Mobile Device Management (MDM) to assign an app to a specific user or device. Your choice affects how that app and its data are backed up and restored.
If you assign an app to a specific device
An iPhone, iPad, or iPod touch with iOS 9.3 or later includes local app data in backups. For example, the backup includes documents and settings.
When the user restores the device from a backup, assigned apps first appear in a "Waiting..." state. Once the user uses MDM to reinstall the apps, documents and settings are available.
In previous versions of iOS 9, a backup doesn’t restore app data. Users of those versions should use iCloud Drive or a similar service to store documents.
If you assign an app to a specific user
If you assign an app to a specific user, the app and the user's local documents and settings restore from the backup.