Hi Barta, I'm part of the team that leads up the design system and its assets. Sorry to hear that not having an XD option is making things difficult. I also work on personal items on a PC with XD at home, or in Linux for fun, so I understand the pain of Mac only options.

That being said, Sketch currently is the gold standard when it comes to providing a top-notch, repeatable, auto-update-able design systems right now. In other words, Sketch users can stay evergreen with the latest standards at any time, unlike XD's management system. Also, we have found many of our internal teams, partners, etc. have access to and prefer to use Sketch.

However, there are a few solutions for PC users.

1. XD allows the import of Sketch files, even on PC. There are occasional bugs in the conversion, and you may lose a lot of the really nice responsive features Sketch provides. You would still need to visit the site to download latest updates of the system as they release (typically about once a month).
2. Or you could try Lunacy, which when I last tested doesn't render fonts properly, nor allows auto-updates.

This Sketch decision was not made lightly, and we re-evaluate this decision semi-regularly. I appreciate you reaching out with your concerns.