System native Python

sudo easy_install pip
sudo pip install aquaduct

The drawback of using system Python installation is a lack of PyMOL. It should be, however, relatively easy to compile PyMOL on your own. Try to follow compilation instruction under BSD systems.

Custom Python

This is recommended way of Aqua-Duct installation. If you do not have custom Python installation you can get it by using one of package managers available for macOS, for example homebrew. With this package manager you can do following:

brew install python
sudo easy_install pip
sudo pip install aquaduct

Next, you can install PyMOL:

brew install pymol
brew cask install xquartz

Once XQuartz is installed you should reboot. The above procedure installs PyMOL, however, PyMOL Python modules are not visible. To fix it you can issue following commands:

cd /usr/local/lib/python2.7/site-packages
sudo ln -s /usr/local/Cellar/pymol/*/libexec/lib/python2.7/site-packages/* ./

The above instruction assumes that you are using brew and you have only one PyMOL installation.