Creating Enhanced Package Connections
Marketing Cloud uses installed packages to connect with CRM and allow sales and marketing users to view Marketing Cloud data in CRM.
As of August 1, 2019, all new packages are created as enhanced packages. Pre-existing legacy packages and their integrations are not affected. See Installed Package Types in the Salesforce documentation for more information.
Admins can create and edit Marketing Cloud connections with enhanced packages in the Marketing Cloud Administration Console page. The Marketing Cloud Connection Management section contains a new Enhanced Package check box indicating the use of an enhanced package. When creating a new connection, the Enhanced Package field is automatically selected and requires the admin to provide the authentication base URI. Admins can deselect the Enhanced Package field when using a legacy package.
See Creating a Marketing Cloud Instance for more information.