Sorry man, I know how hard it is to get into this because I only started electronics 10 months ago, and I know how hard Linux is because I did a course decades ago - I gave up on Linux because I just wanted to use the PC, not build it every time I want to use it -.
The first thing I think is a problem is the jpg. FZ doesn't have a 'for Production' jpg, only the higher quality pdf and svg.
Go File/Export/for Production/Etchable PDF. Assign a folder, and save the export there. Now print from the PDF and set printer to darkest in it's settings.
I use the free PDFXCHANGE Viewer, because you kind-off need the advanced features to scale the print so it's dimensionally accurate, plus other stuff.