There are third-party plugins like Markzware Q2ID that can convert Quark 8.5 files directly into InDesign.
A push toward digital publishing before the industry fully pivoted to HTML5.
While it might be tempting to hunt for a "QuarkXPress 8.5 -2010- Key -App--MULTi- Download" to bypass costs, downloading legacy software from unofficial sources carries significant risks and often leads to more headaches than solutions.
If you are searching for this specific version because you have old .qxp files you need to open, there are safer ways to do it:
A much more affordable, modern alternative to the "Big Two" that offers high-end layout capabilities without the subscription model.
The current version of QuarkXPress can open older files and convert them to modern formats. They often offer a "Free Trial" which might be enough to export your legacy work.