PyOP2 requires Python 3.6 or later.
The main testing platform for PyOP2 is Ubuntu 18.04 64-bit with Python 3.6. Later Ubuntu versions should also work. Some users successfully use PyOP2 on Mac OS X.
Installation of the dependencies is somewhat involved, and therefore the recommended way to obtain PyOP2 is by using the Firedrake installation script. This will give you a Python 3 venv that contains a working PyOP2 installation.