Installing and using Clawpack requires the following:
Mac OS X: For the Fortran packages, you need to have the Xcode developer tools installed in order to have make working. PyClaw does not require make.
See Fortran Compilers for more about which compilers work well with Clawpack.
Python Version 3.0 or above (much of the code works in Python2, but this is no longer officially supported; see Dropping support for Python 2.7).
NumPy (for PyClaw/VisClaw)
matplotlib (for PyClaw/VisClaw)
There are many ways to install the Python scientific stack, e.g. via apt-get or brew. On MacOS, you might check out ScipySuperpack for Homebrew.
If you are installing via pip install then you need pip. If you need to install it, see https://pip.pypa.io/en/stable/installation/
The version of pip install suggested for Quick Installation of all packages with pip requires a recent version of pip, so you may need to upgrade if you run into problems.
If you are installing via pip using the command in Quick Installation of all packages with pip, or via git clone, then you need Git. You may already have it; in particular the Xcode tools on Mac OSX contains Git. If you need to install it, see the Git book.