Before you begin updating your products in your Google Shopping feed, follow these steps:
1. Make sure you have products ready in Google Shopping.
2. Disable the password in your store.
3. You need to claim and verify your store in Google Shopping.
4. Head on to your Google Shopping account and enter your store address in the business information.
5. Click on Unclaimed.
6. Verify your store URL by copying the HTML tag provided by Google into your store.
7. Head over to your store theme. liquid and paste the snippet under the <head> and save it.
8. Head back to your Google Shopping and click on Verify URL and you are good to go.
9. In Stock Sync, you need to input the Merchant ID that you receive from Google Shopping. 
10. To get the Merchant ID, you can sign in to your payments profile. Then, find at the top for Settings.
11. Find the "Public merchant profile", then find your merchant ID.
12. Field mapping currently supports only 3 fields which are SKU, Quantity, and Price.