Why not just also get winplot? (Free on the summa website). You can then just go from illy to winplot and don’t need to mess with any settings in onyx
I was using onyx but the cut server was a bit of a PITA and I needed to change the settings on the summa in the cut server to cut to usb instead of cut to file and send that file to the cutter control folder.
If you really wanted to use onyx;
open onyx, go to cut server. In the cut server configure your cutter to cut to USB (or IP address, whatever you have) and turn off the automatically cutting new files.
I believe onyx takes SVG files and don’t think you need to save things as CutContour so you just file - open your SVG file** and make sure it all looks good. If you’re happy with it (right number of copies etc) then just hit “cut now” down the bottom of the cut server.
**note; sometimes onyx opens SVG files a bit funky and lines are all over the place/artwork is wrong. Just open then resave the SVG and it should work.