Root shouldn’t be blocked, so I’ll recommend sshing from that. Afterwards, you can enable shell for the needed accounts. As for redis, I can confirm it doesn’t need a login.
To connect with root, you can add your SSH Key to the droplet and then SSH .
As for another users, you’ll need to edit your sshd_config for that.
$ sudo vi /etc/ssh/sshd_config
Add or edit the following line
Replace “users” with your username. You can also specify more than one user as shown below.
AllowUsers sk newUserName
Once, you’ve allowed/enabled SSH for the needed user, save the file and restart sshd
sudo systemctl restart sshd