You should be able to use either the short user name which is the name of your home user folder or you should be able to use the full or long user name.
Is this the only user account on the computer? I've encountered a macOS bug where the last user account created "disappears" as a login option. If you cannot log in by typing your user name & password, then perhaps you have encountered this bug as well. If you are encountering the macOS bug, then you will need to create another admin user account. I can provide instructions if you cannot log in by typing out the user name and resetting the Login options as mentioned by @Old Toad.