One of the annoying and occasionally confusing aspects of working on a Mac, or any other Apple device for that matter, is their language. They often turn out phrases that seem to put blame on you, the user, or seem to alert you to a 'problem' that is not a problem at all but simply a signal to take a certain step to carry on with what you're doing.
There is no problem. No problem with you. It's Apple who has a problem with their language.
This is a message that comes up when you start up your Mac. Here there is no problem with your iCloud or your gmail account. You don't need to fix this problem.
It is merely an invitation to log in into your iCloud account. Click on iCloud Preferences and type in your Apple ID password.