Make sure qmake is referenced in the PATH variable
Make sure the location of MySQL on your machine matches the location they specified in the command i.e. /usr/local/include. (Homebrew install location is usually /usr/local/Cellar/mysql/<version>...)
We'll have to figure out a better way to store db credentials. For now you'll have to edit herocontroller.cpp to put in your db user, host and password.