The SF Vehicles example is based on Gradle. You can use Android Studio to import the project. You will also need to register for and add a Google Maps API key.
Follow the instructions for setting up Google Maps for Android. You need to obtain an API key and add it to the AndroidManifest.xml.
SF Vehicles loads realtime transit data from a transit open data set maintained by Firebase.
This sample loads its Firebase and GeoFire dependencies from Maven Central. If you modify and build GeoFire locally make sure to update to modify the gradle file to load GeoFire either directly or from your local maven repo.