brew install sdl2
brew install sdl2_image
brew install sdl2_ttf
brew install mixer
brew install lua

To install brew visit https://brew.sh.

To discover the correct paths you should invoke:

sdl2-config --cflags

and:

sdl2-config --libs

NOTE:

Rather than using #include <SDL2/SDL.h> you can now just use #include <SDL.h>.