You must first set up your local Android development environment. This involves installing the Android SDK. 

More info at https://developer.android.com/studio/index.html#downloads. 

With the SDK setup complete, follow these steps to build the app:

      1. Download the source code
      2. Untar with tar -xvf android_source.tar.gz
      3. cd to the android directory
      4. Build the project using one of the following commands:
        • For a debug APK: ./gradlew assembleDebug
        • For a release APK: ./gradlew assembleRelease
        • For a release App Bundle: ./gradlew bundleRelease
      5. The result can be found in:
        • Debug APK: app/build/outputs/apk/normal/debug/app-normal-debug.apk
        • Release APK: app/build/outputs/apk/normal/release/app-normal-release.apk
        • Release App Bundle: app/build/outputs/bundle/normalRelease/app-normal-release.aab

For a release build, you will need to use a "keystore" file. You may supply your own. If you would like to use the same keystore that we use for build through our website, please first purchase a license and then contact us. Please put the release.keystore file in the same directory that the android directory is in. 

When using a custom keystore, you can set the keystore file location and password in android/app/build.gradle and then use the commands above.