I searched the Knowledge-base for that device and found THIS solution. Hopefully there is some information in there that can help you.
i can't seem to get a user account for scanning to work unless i use administrator and i belive it has to do with it being a subfolder.
Basically the account would have access to the actual folder that's going to store the data,
but not neccesserily the parent folder/s.
I have tried giving full control the the account to no avail, and i can't really find any logs so i just get the printed report and error on the display saying the login failed, but not sure What actually failed, but it seems to be permissions as the account works fine for me, and administrator works fine for the printer.
Am i missing something?