I have SO many problems with Steam, this one has been happening for a while. Every time I launch a game, a notification pops up saying "The in-game overlays require accessibility to be enabled, enable it now from your settings" So, I go onto my iMac settings, and it's already turned on. So I check Steam preferences, it's turned on. And that is when I get confused. I have tried turning it off, restarting my computer, re-installing Steam. And much more. It's been going on for so long now, and it means I can't open alt+tab menu and it also means I can't download mods and it means many more things, so...
Since you are running on a MAC Operating System I have found an article that has been published on the Apple website discussion page concerning your question:
- Quit Steam and create a backup or two with Time Machine.
- Open Finder and press Cmd + Shift + G and enter
- Find the file
com.apple.systempreferences.plistand move it (not copy) to your desktop.
- Restart your PC and test Steam.
If it's working delete the
.plistfile from your desktop. If not, return it to the
~/Library/Preferencesfolder (overwriting the new copy). Note though that this will likely destroy some system preferences; because of this it may be safer to use a plist editor.
This client is running a MAC Operating System as well, and seems to have the same issue. If you read the top comment / answer by Eric Root, it explains the instructions for this problem that is occurring in regards to the Steam overlay.