At this time, JetBackup MC requires Root Access privilege enabled on your server(s) to transfer the SSH keys to your remote server(s) in order to successfully authenticate and establish connection.
Your JetBackup MC root public key is stored here:
/usr/local/jetapps/etc/jetbackupmc/privatekeys/root.rsa.pub
JetBackup MC generates this key automatically upon installation.
First make sure that PermitRootLogin in your SSH configuration file is either set to "yes" or "without-password".
/etc/ssh/sshd_config
PermitRootLogin yes
OR
PermitRootLogin without-password
service sshd restart