Hi Woody
My apologies, I gave wrong informaton in my previous post.. The maintenance script doesn't backup your database, it clears out old call recordings, voicemails, faxes, etc. to maintain disk space.
In my experience, the Advanced > Backup in the GUI has never worked.
By config file, you probably mean the database. The database holds all of your FusionPBX config data (domains, extensions, theme, users, settings, etc.).
If you were trying to download actual call recording files, voicemail files, fax files, etc. that would be a file level backup.
You can configure FusionPBX to create a backup of your database daily and store it locally on your server. You can then SCP into your server or rsync your backup to a remote server to retrieve it.
Steps for configuring your database backup are documented here:
http://fusionpbx-docs.readthedocs.io/en/latest/getting_started/backup.html
Follow the steps under "Command Line" and "Crontab"
Make sure to give your script execute permissions after you create it (that isn't documented in the link above, but it's implied you already know to do that). Ex: chmod +x fusionpbx-backup.sh