Re: Sims 4 won't start on my mac!
Please can you provide more information about your Mac. Instructions on how to do so and what to provide here - http://answers.ea.com/t5/The-Sims-Mac/READ-FIRST-Sims-4-Mac-Help-Guides-and-Troubleshooting/m-p/4612396/highlight/true#M162
Have you disabled Origin in-game - https://bluebellflora.com/2017/12/23/disable-origin-in-game/
What caches did you clear? Mac users have the Origin reset tool - https://help.ea.com/en-gb/help/origin/origin/how-to-reset-origin-on-mac/
Have you tried playing in a new user account on your Mac?