If you get Can't find emacs in your PATH when trying to install Doom Emacs on your Mac you… just… need to install Emacs first! 
brew install emacs
OR if you want to use the Emacs Plus homebrew formula:
Emacs Plus is GNU Emacs formulae for macOS Homebrew package manager. It offers a wide rage of extra functionality over regular Emacs package. Emacs Plus intent is to give the most of ‘plus’ stuff by default, leaving only controversial options as opt-in.
First see which icon you want to use from here then replace --with-modern-doom3-icon with it on the second line:
brew tap d12frosted/emacs-plus
brew install emacs-plus --with-modern-doom3-icon
git clone --depth 1 https://github.com/hlissner/doom-emacs ~/.emacs.d
~/.emacs.d/bin/doom install
It should then be installed 
