While some consider 20-year-old games "abandonware," Myst IV is still actively sold and protected by Ubisoft. Using unauthorized free download sites puts your computer at risk and doesn't support the preservation of the series.
If you find an old physical copy or a digital download isn't launching, try these steps: Myst IV: Revelation Free Download
In that same Compatibility tab, check "Run this program as an administrator." While some consider 20-year-old games "abandonware," Myst IV