If you're not part of the group that the folder is shared with, then you will only be able to access the folder from within the Admin Console. You'll be able to manage all the content and permissions for the folder from there. However, you won't have access to that folder from the Files page or on your desktop if you have the app installed.
You'll still be able to see activities for this folder when creating activity reports within the Admin console too.
I hope that helps, let me know if you have any other questions - thanks!