How to enable SSH access for non root users

Following the recommendations in online forums, I have configured my new Ubuntu server so that root can only be accessed via my private key.

My understanding is that I’m also supposed to create a different user account that will be used to handle root-like tasks via elevated privileges and sudo. I can create that account with appropriate privileges, but the server will not allow me to connect via SSH. The only way I can use the other account to access the server is via the Digital Ocean console. The console does not play well with my Mac’s external keyboard.

What do I need to do to enable SSH connections to other accounts? I have found instructions online which suggest changing PermitRootLogin from ‘no’ to ‘yes,’ but that seems to defeat the point of using an encrypted key to control root access. I cannot find instructions which explain how to allow password authentication for everyone EXCEPT the root user.