It is not as intuitive as Procreate or standard SketchBook. It requires learning hotkeys and understanding how vectors interact with rasters. However, once mastered, the speed at which you can iterate on product concepts is unmatched by many modern apps.
While legacy free trials existed years ago, Autodesk no longer hosts these downloads or provides licenses for them. Official Discontinuation: autodesk sketchbook designer 2013 mac osx free
If you have a physical box or an old email with a serial number, you might be able to install from a backup .dmg . However, macOS Catalina (10.15) and later dropped support for entirely. SketchBook Designer 2013 is a 32-bit app. It will not launch on macOS Catalina, Big Sur, Monterey, Ventura, Sonoma, or Sequoia. It is not as intuitive as Procreate or standard SketchBook
About the Author: A writer exploring the intersection of ancient tradition and modern chaos. While legacy free trials existed years ago, Autodesk
If you are unable to locate a compatible installer for the 2013 version, several modern alternatives offer similar professional features for free: