How to get scanned documents into a database

All my scans are in pdf format; single or multiple pages
This is a setting on your scanner software

More information might be available if you identify your scanner and software
Personally, I use a scanner app on my iPad (iPad camera) with pdf file enabled
I use the IOS share menu to import the scan pdf to DTTG

how to get the scanned documents into a database?

On my Mac, I would direct the scanned documents to the Global Inbox folder
This is described at the post linked below: I use an alias folder on my desktop

The scanned pages are in a group I created

I don’t use any groups, just the pdf file tagged as required