I don't know what I did but the Print Settings' GUI does not have this message anymore:
Printing service not available. Start the service on this computer or connect to another server.
Also, on the upper right corner of the GUI there is an Unlock button. I clicked it and entered my password and now the Add button can be clicked (not greyed out).
I'm not really sure what I did. Could it be that I installed cups? I installed many apps including:
vlc player, kdenlive, smbclient, samba, cifs-utils, gimp, wget, inxi, arp-scan, nmap, seamonkey browser, gparted, virtualbox.
Anyway it's working now, I'll try to add an Epson printer.
Thank you.