This error means that the app has experienced an authentication error and can't verify your account information. Please retry the action, and if that doesn't work, force close and reopen the app.
Please see the following articles on how to force close an app on:
If that still doesn't help, please make sure you have the latest update of Explain Everything Whiteboard installed on your device. To do this, simply follow the same steps as you would when downloading the app. If there's no Update option in the store, this means you have the latest version available for your device.
If that still doesn't help, please sign out of your account and sign in again.
To sign out of your account, please open your Main Menu '...' in the top right corner and tap on your username. On the Profile page that appears, you will see what email address you signed in with. From here, you can log out by tapping on the 'Edit Profile' button in the top right corner of this page and selecting the 'Sign out' option. You will return to the sign-in screen, where you can now tap 'Sign in or create an account'.