NextcloudPi- What to back up and how

I’d like to use a nextcloud instance only for calendar, notes and contacts, running on a raspberry pi 3B+.
It is already installed, but before I switch over all family members to this, I’d like to ensure it’s being backed up daily to my NAS, so in case the SD card brakes or I lose all data, I can restore all calendars, files (notes) and contacts.

What folders do I need to back up?
How do I back up the database?
How would I restore it after a crash and a fresh installation?

Again, only for calendar, contacts and notes, plus if possible users and their passwords.
We are 4 users with about 4 calendars each, not so big.

I tried playing with rsync, it seems to work but does not include the database as far as I can see.
Is there any good tut or a manual?

Many thanks

I am using nc-backup-auto to do this.

Have you noticed How to backup and restore a NextCloudPi instance using ncp config already?

I saw the function and it is also available through the NextcloudPi Admin page.
I tried setting up r-sync, but for some reason the system keeps asking for a password.