This article helps you connect your Google Ads account. Ad360 will then be able to run and manage ads in your Google Ads account on your behalf.
Your Google Ads account Id is a unique number provided by Google and used to identify your Google Ads account.
You need an existing Google Ads account to perform this action.
You can find your Google Ads account Id in your Google Ads account by clicking on the help icon in the top right corner.
Detailed instructions:
1. Sign in to your Google Ads account.
2. Click the help icon 
3. Find “Customer ID” at the bottom of the menu.
Source: Google Ads Help. If you weren't able to find your Google Ads account ID, you can find more information in this Google support article: https://support.google.com/google-ads/answer/1704344?hl=en
Note that your Google Ads account must not be under a Google Manager Account (also known as MCC account) if you want to connect to Ad360. If this is a blocking factor, please reach out to your Ad360 Account Manager or email the support.