If you are logging in with your Manager credentials, you may not have the right permissions to view the Groups. Set up a test account (click 'Add an organization' on the Dashboard) and log in with these details. If you still can't see the Groups, go to the Edit page of each Group and check that the 'Can book meetings' box is checked. If you still can't see the same Groups or if you are having other problems, please create a support ticket at the top of this page.
To learn more about creating and managing Groups, visit this article.