How to print
When printing from Apple computers. You will sometimes run into this error message asking for a password of an administrator. Use your Netpass credentials (note: in the name section, it may say "labuser." If so, just delete this and put in your Netpass user name.) Do not check the box that says "Remember this password in my keychain"
After you have entered your Netpass information, a PaperCut login screen will appear. Enter your information here as well and then click ok.
Once you enter your credentials your print job will have been completed and you will see the Print Information screen.
Reference
https://www.papercut.com/support/resources/manuals/ng-mf/common/topics/authenticate-print-about.html