It's been a minute since I've used Macos, but if memory serves correctly, Macos doesn't send the key code corresponding to meta when you hit the option key, so that's probably part of the challenge. I know iTerm2 had an option to fix that when I was using Macos, but I'm not sure if that's still true.
Some quick research reveals this article on the Emacs Wiki with some hints. https://www.emacswiki.org/emacs/MetaKeyProblems