I’ll take up the glove 
Plain rsync is a bit off topic in the other thread, let me put it here.
What do you want to back up?
For a backup of the (whole) Debian installation on the SD-card, rsync is less suitable. For that you’d use imaging software. If the goal is ‘minimal fuss, get it backed up till Archivist/Borg is installed’, I’d shut down the server for ten minutes and dd the whole SD-card to the project / backup directory on my workstation.
If the goal is to sync a specific part of the running Debian installation, it works quite straight forward. On your workstation:
$ mkdir -p /home/frittro/yunobackups/backup1/ # or another place of course
$ rsync --progress -a -e ssh frittro@fmds:/home/ /home/frittro/yunobackups/backup1/
$
Source is on the other side of ssh, destination is in the directory on your workstation you reserved for it.
The command is very straight forward, give it a try copying something from one directory to another directory on your workstation (in that case you can still use SSH, but you can also omit the -e ssh frittro@fmds:-part to make a local copy)