This article explains how to connect your Google Analytics account to Ad360 App for Shopify.

To make the connection, you first need to choose which Google Analytics View to connect. 
A view is the lowest level of your Google Analytics account (Account > Property > View).

Ad360 needs the correct ID of the Google Analytics View to start collecting relevant data to optimise your demand generation activities.

You need an existing Google Analytics account to perform this action.

You can find your View Id in your Google Analytics account by going to the Admin panel and clicking on View Settings.

Detailed instructions:

1. Sign in to Google Analytics.

2. Click Admin, and navigate to View.

3. In the VIEW column, click View Settings.

4. View ID places in Basic Settings

Source: Stackoverflow. If you weren't able to find your Google Analytics View ID, you can find more information in this Stackoverflow thread: https://stackoverflow.com/questions/36898103/what-is-a-viewid-in-google-analytics