@fluffyvmpr
@puzzlezaddict has covered all the issues with your game but If I could just reiterate:
- Your Mac is NOT supported as it has Intel HD 6000 graphics and a Broadwell CPU, the worst possible combination to try to get the game running (listed here). You are also running an unsupported version of macOS.
- 3rd party 'clean up' apps are appalling and should never be used. They quite often delete files they shouldn't and can cause instability of the OS by doing so. You should manually uninstall the game by following the instructions in my guide that Puzzlez linked to. It may be a faff for you but it is the only guaranteed way to get rid of ALL residual files left behind by the uninstaller. Just searching in Finder is not going to find them as they are in your hidden Library folder. Trust me, I have fully tested this myself many times over the last 8 years on every single version of macOS since the game was launched and I regularly update my pages if anything new is found.
- Forget Origin to try and get your game running. It is NOT needed to play the game or even install it, only to download the .dmg. There is also no repair function for Sims 3. You could even delete Origin from your Mac and Sims 3 would still run.
- MacBook Airs are great but they really aren't gaming machines. You have a dual core CPU and an integrated graphics chip. Sims 3 is not a natively written app for macOS, it is the Windows version 'wrapped' using Cider. Sims 4 is natively written for macOS so there is no comparison. Because of Cider your Mac is having to work extra hard just to get your game to load, let alone play. There is also the 2Gb RAM limit for the game.
