These are the core oTree libraries.
http://otree.readthedocs.io/en/latest/index.html
pip install --upgrade otree-core
otree startproject oTree
otree resetdb
otree runserver
If you are modifying otree-core locally, clone or download this repo, then run this from the project root:
pip install -e .
cd .. # or wherever you will start your project
otree startproject oTree
otree resetdb
otree runserver
See this document that explains how oTree differs from a typical Django project.