1. Login to your Merchant Center account here: https://merchants.google.com/
2. Navigate to “Tools” then to “Account Access” under the wrench icon.
3. Next, click the blue plus button and enter firstname.lastname@example.org. Then click “Add User.”
4. Last, click the user you just added (my email address), and make sure the “Admin” and “Google Customer Reviews manager” boxes are ticked.