The app used by the umpire to register points in a match works on most Android devices, as long as they are not too old (Android version 5 or newer).
To install the app on your device you need access to Google Play Store, and for that you need a Google account on your device. Instructions how to get onte can be found here: https://support.google.com/googleplay/answer/2521798?hl=sv.
Here's a direct link to the app on Google Play Store: https://play.google.com/store/apps/details?id=com.eltok.scoreboardliveumpireapp
or
Open Google Play Store on your device and search for Scoreboard Live Umpire. In the search results, look för Scoreboard Live Umpire by Christian Olsson and click Install
To be able to use the device it needs to be registered with the Scoreboard Live web site. The first time the umpire app is opened, a label No connection will show in red at the bottom of the app start screen.
The next step is to register the device on the scoreboardlive.se website.
An activation code will appear in green on the screen. Head back to the settings screen in the umpire application:
If the activation code is correct, the device will be registered with the scoreboardlive.se webpage.
When all settings are done, press the back button to go back to the app start screen. If all is well, a green label Connected will show at the bottom of the screen.