If you get  “Insufficient User Permissions” “You have not been designated as a Marketing Cloud Connector user. Please contact your system administrator.”

1. Enable Marketing Cloud for AppExchange User check box for the Marketing Cloud user.

2. Enable Marketing Cloud for AppExchange Admin User check box for the Marketing Cloud user.

If you don’t see the fields in the User detail page, add the fields to the page layout or run the below code to update the user in the developer console

update new User( Id = ‘Id of the user’, et4ae5_ExactTargetForAppExchangeAdmin__c = true, et4ae5_ExactTargetForAppExchangeUser__c = true);