If you backup your data to Arq and then wish to retrieve data from the backup while away from your usual computer, you would need to dowload the entire database from Arq; you cannot retrieve individual documents from the Arq backup of you Devonthink database without downloading the whole database and running DT3.
That’s the problem I had; my database(s) are so large that it is not feasible to do such a download when traveling. I can download 1 file at a time through DT3 web server but that is not realistic either. . Better would be a way to retrieve a specific nested group(s) and its related documents.