Sorry I’m just a not expert user and I’ not really easy with English language
No worries! Your English is easily understood. There are just technical terms that are unclear.
When I have a new document means PDF or email or Word, I save it on my desk and after I dropped the new document in the right folder through le DV interface.
But I don’t find the document in the folder in iCloud - and I have to go though DV interface for finding the document.
If you just drag and drop a document into DEVONthink, it is copied into the database. So I’m not sure why you’d expect something to appear in iCloud (and if you’re referring to iCloud Drive on your Mac or online).