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From "System requirements for AutoCAD for Mac 2021":
Supported Operating Systems:
Apple® macOS® Catalina v10.15
Apple macOS Mojave v10.14
Apple macOS High Sierra v10.13

For more information look here:
https://knowledge.autodesk.com/support/autocad/troubleshooting/caas/sfdcarticles/sfdcarticles/System...