Postgres.app is the quickest, easiest way to start working with PostgreSQL on your Mac.
It is strongly advised that you do not use Postgres.app in a production environment. However, for learning about PostgreSQL and using extensions such as PostGIS, Postgres.app makes server installation and set up a snap.
Installing Postgres.app
Download the disk image for the application. Move the Postgres.app application to /Applications and then launch.
You will also want to see how to modify your $PATH to access the included command line tools.
Note on Foreign Data Wrappers
Some of the FDW libraries are included with Postgres.app, however the OGR FDW extension is not included, so the portion of the workshop will not be able to be completed using Postgres.app.