Unable to connect with WP Fusion

I encountered an issue when I try to connect WP Fusion and Keap. Here is the error message. Can you please advise on we can solve this?

Error: Infusionsoft API call failed with method DataService.getAppSetting. Message: [InvalidConfig]

Unfortunately there is not sufficient information here for us to assist you. I would recommend contacting WPFusion for help with their application, which is generating the error.