I've used rsync in the past, but I only used it to:

create a local backup
grab files from a remote rsync server for a mirror.
updated a remote server over SSH.

In this tutorial, I am going to show you how you can set up your server to accept rsync connections with a separate user/authentication list to your computer's local user accounts. This is more like samba or FTP where your server accepts file transfers with login details that aren't local users.

Backup your Synology on a Raspberry runnign a rsync server with hyperbackup