I think you need to Clean Uninstall AutoCAD as described here:
https://knowledge.autodesk.com/support/autocad-for-mac/learn-explore/caas/sfdcarticles/sfdcarticles/...
or here:
https://knowledge.autodesk.com/search-result/caas/sfdcarticles/sfdcarticles/Clean-uninstall-of-Autod...
And then install again. Don't forget to install latest Update after you install AutoCAD again:
https://knowledge.autodesk.com/support/autocad-lt-for-mac/downloads/caas/downloads/content/autocad-l...