I just got a new larger format printer, Epson XP-150000. I can see the printer in MacOS settings. I can print to it from other programs like Preview, MS Word, GIMP, and Digikam. When I go to the print page in Darktable, the printer isn’t in the list of available printers.
To make things more complex, sometimes Darktable doesn’t even show the OS default printer in the list, either. If I shutdown Darktable and restart it, then at least I see the default printer, but I’ve never seen my new printer in the list.
I may be wrong, but I think the print module only works on the Linux based systems, and that you’ll have to export to one of your other programs (GIMP works well) in order to print your images edited in darktable.
MacOS also uses CUPS, which is the same print subsystem as Linux. I’ve been printing for a long time from DT, so I know it supports printing in MacOS. It’s a matter of DT loading the printer list. I think it might be a bug, so I opened a bug report on GitHub.