We tried to make OpenKM as intuitive as possible, but an advice is always welcome.
Forum rules: Please, before asking something see the documentation wiki or use the search feature of the forum. And remember we don't have a crystal ball or mental readers, so if you post about an issue tell us which OpenKM are you using and also the browser and operating system version. For more info read How to Report Bugs Effectively.
Could be some problem with installaed java version. Try scanner with our online demo and open java console looking for some error. Post here if appearing some.
In order to scan a multipage document you need a scanner with a document feeder. This way you put all the document pages and the scanner will get and scan every page automatically.