Google Analytics Settings and API Client Id

I just installed the Easy Google Analytics for WordPress plugin and the installation was easy but I got lost in the settings screen.
It ask me for the API Client Id and provides a link to a tutorial:
https://developers.google.com/api-client-library/javascript/start/start-js#Setup
But this tutorial it’s quite generic and I am not sure about what I have to do to get the API Client Id.
Can anyone give some advice?

https://wordpress.org/plugins/easy-google-analytics-for-wordpress/