1. Allow all scheduled sends to complete before starting the upgrade, if possible.
2. Ensure that you can log in to Marketing Cloud using the current API user credentials.
3. To minimize downtime if an unexpected error occurs, schedule the upgrade during off-peak hours.
4. Follow the steps to install the managed package.
5. After upgrading, existing Marketing Cloud Connect users are prompted to reenter their Marketing Cloud credentials the next time they access Marketing Cloud Connect.