Why does the error Storage Limit Exceeded mean when connecting my Mailchimp Account?

Salesforce enforces storage limits in sandboxes and developer orgs. Our app needs to create records when you first connect your mailchimp account, so we won't be able to finish connecting if you run out of storage. 

Recommendations:

• Use a sandbox with a larger storage limit. See Salesforce Help for more info.
• Use a free/test Mailchimp account with less data.