Figured it out. The VM's in cloud engine don't come with a root password setup by default so you'll first need to change the password using
sudo passwd
If you do everything correctly, it should do something like this:
user@server[~]# sudo passwd
Changing password for user root.
New password:
Retype new password:
passwd: all authentication tokens updated successfully.
cat /etc/ssh/sshd_config PermitRootLogin yes
PasswordAuthentication yes
systemctl restart sshd