Custom Maps can use almost any map image as a GPS map. The map image can be provided in JPG, PNG, GIF, or PDF format. If a PDF file is used the user must select the map page from the PDF document, and the page is converted into JPG image before it is used as a GPS map.
The project can be directly imported to Android Studio, but before it can be successfully built, it has to be provided a Google Maps API key, as a string resource named "google_maps_key". This is typically done by creating file "google_maps_api.xml" in app/src/main/res/values directory, and the file should contain only that one string resource. More details for getting a Google Maps API key can be found at https://developers.google.com/maps/documentation/android-sdk/get-api-key.