cupsd seems to require libavahi, and i refuse to install any software by this UNIX-ruining Lennart Poettering. (avahi, pulseaudio, systemd)For me it work with cups-pdf installed and cupsd running.
In Librewolf options i have an exception for https://forums.freebsd.org to be able to use cookies and site data, and its the only site i can print as pdf. So it must be something about security/privacy options.I also had this problem, I thought it was because I hardened the user.js, but not, I can't remember well but try to disable your firewall (pf for me) and test. I managed to block access to printers with a poorly made pf.conf...