Welcome to the forum!
First I should probably tell you that Inkscape doesn't support CMYK yet. So possibly that's part of the problem, if the printer is expecting it? Not that I really understand much about either printing or cmyk. But just to let you know.
Inkscape's background is transparent by default. So if you don't change it, it will be transparent. There is an option to display the grayscale checkerboard which most graphics programs use to indicate transparecy. I don't know if the machine might recognize that and respect the transparency?
In any case, Inkscape's printing capabilities are extremely basic. So much so that we typically suggest saving the file as PDF, and using a PDF viewer to print from, if you need anything more than a simple page print.
Inkscape does have an extension to produce CMYK (in a PDF file, I think). If I'm not mistaken though, it might or might not work with Windows. Here's that extension, if you'd like to try it.
https://inkscape.org/~wout/★output-pro also
https://github.com/wout/Inkscape-OUTPUT-PROGiven all this info, if you still think Inkscape isn't performing properly, you're welcome to file a bug report:
https://gitlab.com/inkscape/inbox/issues (click the green New Issue button) (more info about how to make a bug report, if you need it:
https://inkscape.org/contribute/report-bugs/)