...It can do anything from building, uploading, and then promoting your App Bundle or APK to publishing app listings and other metadata. The first APK or App Bundle needs to be uploaded via the Google Play Console because registering the app with the Play Store cannot be done using the Play Developer API. For all subsequent uploads and changes, GPP may be used. To successfully upload apps to the Play Store, they must be signed with your developer key. Make sure you have a valid signing configuration. After you've gone through the Service Account setup, you should have a JSON file with your private key. ...