John, are you a Magix representative? If so I would like to just transfer my SF Pro 3 license I just purchased from the Mac to Windows 10 since Magix is not supporting the new Mac OS. I have been editing on all platforms for over 25 years now, and I agree with the other posters that MAgix needs to make clear which of their products work on the new Macs and which do not.
I can quite categorically say that John (@johnebaker) is NOT a Magix representative. Like all we moderators, he is simply another user of the software, albeit a very experienced one!
If you wish to request and are still eligible for a refund for the SF for MAC software which you have purchased in order to replace it with SF Pro for PC you need to contact Magix Sales. Unfortunately, the route to make such contact has recently become rather more convoluted: you need to press the Additional offers button in the footer of any forum page, scroll to the bottom of the page which opens and find the links for Support. (Having just checked this, I suggest you use the link for Technical Support and on the page that then opens, scroll to the bottom to find a link to "Visit personal service area", log in and then select to contact the Sales team.)