Cannot log into Messages on MacBook

Hello!
Has anyone run into problems where they cannot log in to Messages on MacBook with their Apple ID? I entered my information into the login dialog box, and I received an error message. I have also not been able to login to FaceTime or download updates to Keynote on the App Store (all of this on my MacBook; my iPhone is fine).
My calendar, contacts, notes, and reminders are all synced up correctly, but I have been having problems with the Messages and FaceTime since the latest software update (High Sierra 10.13.2).