Digital Editions download not working_administator not accepted

I tried to download Digital Editions, but as soon as it asks for the permission of the administrator to continue the download, it's not permitted. Even if I swipe my finger (and I are the only person who has such a "swipe-finger-ID" at this laptop), it does not continue the download and tells me that there is a "error 6". Can anybody help me here? That would be awesome! Thanks in advance.