The app may require you to install additional apps. We highly recommend you install F-Droid - a free and open source app marketplace - as not all apps can be found on Google's Play Store and F-Droid is more privacy oriented (no tracking, no account needed) you can download it <a href="https://f-droid.org/FDroid.apk">here</a>.
The app runs a background service to notify on new Disroot state messages. If you want to take full advantage of this feature, you need to disable battery optimization for the app.