Not a DMS user. But with finicky application I do use, the scanner needs to be powered on prior to starting the document management application. Cannot turn scanner on after the application is up and running.
Also I do not use Hosted solution so that's a whole other ball of cornflakes in and of itself potentially.
Here are all Help Articles mentioning DMS
Key is that scanner is TWAIN compliant. In DMS, try using the Help at the right of the top row. Put scanner in the search box and you will get several help articles.
Is DMS installed locally or remotely? I am not familiar with that ball of cornflakes.