This error occurs when the user credentials used to connect given Merchant account don't have sufficient permissions that would allow for product data extraction.
Error: The credentials used to connect this Merchant account don't have the necessary access level. Ensure your user account has at least "Standard" access.
How to resolve this error
To fix this error you need to be an Admin user
Go to Merchant Center account
Click on Settings > Access and services
Go to tab People and access
Under People table find the user account whose credentials were originally used to connect this Merchant account to the Alvie.
Click Manage and ensure that Standard access type is selected and click Save
Read more about different access levels in Google's Merchant Center documentation.
If you encounter any further issues or need additional assistance, please don't hesitate to reach out to the Alvie support team.