there are a lot of articles on the internet on how to check and configure it.
you can also check Certs with WinSCP or via SSH
on your screen you have the wrong username; not root - only should be [administrator@vsphere.local]
The system tells you to provide a username: so you should provide ...administrator@vsphere.local
to ssh you log in with [root] but all replacement actions and confirmation is going via administrator
One more thing - you can reset all certificates with action number 8 - but before do a snapshot;
once it will be reset - you will be able to login to vCenter
after that you will be able to check and decide what to do next