Link your website to your Merchant Center Account
Verify and claim your website URL :
In the Business Information Section
Then you will to verify your domain by adding a meta tag to your layout ( head block section).
Once this done you just need to ask google merchant center to verify your domain.
Switch to Classic Merchant Center
When creating an account, you may be redirected to Google Merchant Center Next.
If you want to switch to the classic version you do the following steps:
1.Click on the "Help" button
2.Click on the "Use classic Merchant Center" button
3.Choose the reason (optional) and click on the "Next" button
4.In the next two screens choose one option that fits you the best
5.Select the checkbox and click on the "change now" button
Get your Google Merchant key for authentication
Merchant Center can automatically create a Google API Console project and associated service account key for you. Your application will authenticate with this key when using the Content API for Shopping.
Select Content API from the cogg menu in Merchant Center
Select the Authentication tab.
Click the + button to create a new API key.
A file called content-api-key.json will be downloaded
Now open content-api-key.json in a text editor and copy its content to your app store settings as well as your merchant ID.
The setup is now finish you will just have now to configure your Tax & Shipping settings. ✊
Next Step: Setup your feeds in the Admin Area.