Error 301 is shown when you try to play with a Guest account and we're not able to determine a Unique Device ID. We need the unique ID to create an account so we can store your progress. The next time you play, the same ID will be used and allow you to continue your progress. In some situations, we can't determine your unique ID, so we ask that you use a different login method. Without a unique ID, you would have to play on an account shared with other players.