Your phone profile has been or needs to be reset. This will temporarily remove some apps and your email account from your phone, and then re-add these again to clear the issue.
You will see your phone background change, and your emails be removed from your phone. After a short while, these will return.
Please open the Gmail app as before, you will then be presented with a login screen, asking for your password. This is the password you use to log onto the computers, not your phone pin.
Enter this, and your phone will then connect to the email system. Your phone may show a message about being quarantined, but do not worry if this happens, it will go by itself. Emails will soon start to download, along with your contacts and calendar, but depending on various things, it may take a few hours.
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