Into the Dead 2 uses either iCloud for iOS devices and Google Play Games for Android devices to save your progress to the cloud. The cloud profile should be created when you load the game, as long as you are logged into your profile.
This means that you should be able to restore your progress if you reinstall the game, or upgrade to a new device.
To access the cloud save system in-game please tap on either the Game Center or Play Games on the right side of the Settings Screen.
You can view your most recent cloud save by tapping on the Cloud Save button on the lower right of the screen.
The cloud save systems are specific to their respective platforms. As such, transferring progress from iCloud to Play Games and vice versa is currently not supported.
For more information about iCloud please follow the link below:
For more information about Google Play Games please follow the link below: https://support.google.com/googleplay/answer/2954594