You need to change the login screen settings beforehand.
With an administrator user account go to:
System Preferences...
Users and Groups
Login Options
select Display login window as: Name and password
Then you will have to type the username and password on the login screen.
You might need to unlock the administrative options by clicking on the padlock and providing the user password for sudo.
But one likely reason for user icon not appearing might be enabled FileVault (full disk encryption). Only users with permissions to unlock the drive would be visible. Refer to this article to see how to change the settings.
System Preferences...
Security & Privacy
FileVault tab
and there you should see a warning message "Some users are not able to unlock the disk" and have a button to add users.