This is likely to be a problem with connected accounts in the “Access work or school” settings page.
On Settings > Accounts > Access work or school, remove any account, restart your computer, and check if you see the “Sync is not available for your account. Contact your system administrator to resolve this.” message.
If you no longer see the message, you can try adding the work or school account again. If not it’s not required, don’t add it back.
Of course, you wouldn’t this if you’re using a PC connected to a Domain. If this is the case, you first want to contact your system administrator.