Anything that prevents you from playing the game properly. Do you have issues playing for the game, downloading it or successfully running it on your computer? Let us know here.
Just bought and installed Factorio from the developer's site after playing the demo on Steam (which ran perfectly fine). Whenever I try to launch it, it immediately crashes without even a loading screen.
Whilst factorio is supposed to support 10.10 and above (and you're on 10.11) from googling your error it seems that it is using something only found in 10.12 and above. Is there a way for you to update to 10.12? Your MacBook does support it.
We probably won't be actively supporting deprecated macOS versions anymore. You can download version https://factorio.com/get-download/1.1.49/alpha/osx (which is the same version as the demo on Steam), or e-mail us to support@factorio.com and ask for a refund. I apologize for the inconvenience.