Pls note that the book does not cover installation instructions for Zen Cart on a local Mac.
Setting up a local Zen Cart store is purely optional and is used mainly as a testing environment to try out different scenarios for your store.
You can also accomplish the same objective if you already have a web host that supports running Zen Cart on their servers. Just install your test Zen Cart store into a sub-directory (e.g. www.example.com/test) separate from your 'live' Zen Cart store (e.g. www.example.com or www.example.com/store).
Check out the 'Certified Hosts' link on the top of this page if you are looking for reliable Zen Cart hosts.