Scan setups are a long way off of simple, and there are many varied ways to do them.
TWAIN/WIA is one
Then there is scanning to a share on the PC, which of course has to be created and shared first
But generically speaking, make sure the port is 445(1) make sure the PC Domain name or Workgroup is before the username(2) or that it is formatted as an email address, no matter the scenario, it will show correct in the below part (picture 2)
For the username, easiest method to get the exact right format is from the share within windows itself ala: <exactly how it shows within the brackets>