Since everyone so far is using the guest accounts, here are a few suggestions:

1. The app logs you in as the first guest account currently not in use, which is usually guest0. The next time you start the app it will try to log you in to the same account again, guest0. If someone else is using guest0 you will get a message that it is in us and use another account. To do this you should be able to select one of the other guest accounts (guest1, guest2, guest3, or tflight1) and press login. Note when the other account line is selected (each line is a button), it will turn green.
2. Please don’t leave the app logged in to a guest account for a long time without playing, so someone else can use it, if they want.