This project has been developed in Android Studio with following version and build:
Android Studio 4.2.1
Build #AI-202.7660.26.42.7351085, built on May 10, 2021
Easiest way is to clone this repository, open it as project in Android Studio and start it using an emulator.
If you want to build an APK, change into root directory of this repository, and run:
$ ./gradlew assembleDebug