In Android studio, this can be done from the Quickstart panel. Just choose "Configure", then "SDK Manager". In the SDK Tools tab of the SDK Manager, make sure that "Android Support Repository" is installed, and that the latest "Android SDK build-tools" are installed. Click "OK" to return to the Quickstart panel. You may also need to install API version 28 in the SDK platforms tab.
1. Open Android Studio. On a new installation, the Quickstart panel will appear. If you have open projects, close them using "File > Close Project" to see the Quickstart panel.
2. From the Quickstart panel, choose "Checkout from Version Control" then "git".
If you would like to build the Huawei Flavor with Huawei HMS push notifications you will need to pass 'huawei' as a command line arg to include the required dependencies.
e.g. `./gradlew assembleHuaweiDebug -Phuawei`
If you are building in Android Studio then add `-Phuawei` to `Preferences > Build, Execution, Deployment > Gradle-Android Compiler > Command-line Options`
Code contributions should be sent via Github as pull requests, from feature branches [as explained here](https://help.github.com/articles/using-pull-requests).