To download and install V-Ray for SketchUp 2017 on a Mac, you typically need to access the archived versions of the software through the official developer, Chaos.
To download V-Ray for SketchUp 2017 on Mac, you must access the Chaos Download Center, which hosts an archive of older versions. While SketchUp 2017 is no longer officially supported by Trimble, specific legacy versions of V-Ray remain compatible with this edition. Compatible V-Ray Versions Download Vray Sketchup 2017 Mac
Conclusion
If you purchased V-Ray 3.x in the past and still have your license credentials: To download and install V-Ray for SketchUp 2017
Here are some tips and tricks to help you get the most out of V-Ray for SketchUp: Download Vray Sketchup 2017 Mac