CUPS Error "credentials are required to print"

I installed NethServer to serve as AD, file sharing and print server (CUPS), but when trying to send a print job the following error appears: credentials are required to print.

I already tried to comment out the AuthType line in the printers.conf file, and it didn’t work either.
Help me please.

credentials_necessary

How exactly did you do this please, and why do you thing this is required?

How and as who did you tiy to send the print job that results in the issue?

I’m having trouble authenticating a user created on nethserver for the print and shared folder services. nethserver does not recognize users and passwords, but I can authenticate via AD with the same users. Example: if you try to access a shared folder you get an authentication error. The same goes for printing.