Can you try adding the API key below, when I do it I get the error message. I’ve never had this problem before and I am hoping you as owner may have workaround? API Hidden
First up, this is a Mailchimp error, not Ourlocality, as the roles are not related to WordPress. It should not make any difference who owns the website, as even the superadmin got the same error with the same API.
A different API worked fine, so there is something wrong with the API.
Check the API page, which should list all attempts to use it, it may have a more helpful error
Make sure API is being used for for this one application only
Test a different API, by creating a new one
This is a Mailchimp plugin, so they should be able to provide support to paying users for errors generated at their end.
Check this post on how to raise a ticket, if you pay for a mailchimp account: