For anyone encountering this error, I have found a post that was tremendously helpful in solving the problem.
See: 5.1.5 buildout chokes on "'extras_require' must be a dictionary" installing BTrees-4.4.1
I had to update my virtualenv zc.buildout and setuptools via pip and then subsequently version pin in my buildout.cfg.
env/bin/pip install --upgrade 'setuptools==40.8.0'
env/bin/pip install --upgrade 'zc.buildout==2.13.1'