How Do I "Install the Google Client Library"

Hi Experts,

I'm trying to get started with the the Google Calendar API, following the steps at https://developers.google.com/google-apps/calendar/quickstart/php

I've completed Step 1, and have my .json file in my test project folder, but I have no idea on Step 2: Install the Google Client Library

My environment is Win 7 Pro, Running IIS with PHP as CGI.  I have never needed to use github, SSH or Linux commands.

I have also checked the alternative installations options, but same thing - none make sense.  I was actually thinking that I could download a set of Google files into my project, then require_one some_file.php, and go.  Sort of PHPMailer and TCPDF.

I actually see this at the start of Step 3, but where is the vendor/autoload.php coming from? Guessing Step 2?

Thanks!