Putty error: No supported authentication methods available (server sent: publickey)

I am trying to setup a server for my wordpress site. I was going through this tutorial (https://www.digitalocean.com/community/tutorials/initial-server-setup-with-ubuntu-16-04) to setup ssh keys. After step five when it says to try logging in with the ssh keys with the newly created user putty returns back with a error saying: “No supported authentication methods available (server sent: publickey)” I put the public key in the authorized_keys file and everything the tutorial said but it still returns that error. If I try logging in to root with the same private key it works fine. It just shows that error when I try logging in with the new user.

Any help would be appreciated.