This is not documented, but you can not configure the store code that is used in the GraphQL request, resulting in problems using the connector.

From Magento 2:

The store that was requested wasn't found. Verify the store and try again.

App:

FetchError: invalid json response body at http://*****/graphql reason: Unexpected token < in JSON at position 0

Source of problem:

If you do not use "default" as your store's default code, then you can not use the connector. This should be resolved by configuration option to support Magento 2 multi-store environments. Similar to setting ENV for backend host, you must also be able to set the store code.