If you disable the password, you need to
define a key.
Code:
$ pwd
/mnt/software/opt/user
$ install -dm 0700 .ssh
$ cat > .ssh/authorized_keys << 'EOF'
ssh-ed25519 q2oorWOQPsssdGMI36WHXmq8BuXp0SRtC3qH8z1Yo1nmF5pyyiyy44hyn7qE25NgGOVF user@domain.com
EOF
$ chmod 0600 .ssh/authorized_keys
I don't know if adding the public key inside the user UI will create the above directory structure with the right permissions. I always do it from terminal, manually.
Following Linux standards, permissions should always have a
022
umask.