Can you install iCloud for Windows on the windows machine? If it’s a work PC, perhaps not but if you can, then there should be no issues using Obsidian on Windows with it. I’ve got an Obsidian notebook in iCloud and it syncs fine on my windows machine that has iCloud installed.
Whilst iCloud for Windows isn’t great, it does generally work I’ve found.
The other option is to pay for the Obsidian sync service, which is platform agnostic.