In accounts where the "auto-grouping" feature is enabled, admin can select an organization from the ones they own on Github.
Navigate to the Details tab in the Meterian dashboard and click "Change..." on the Github organization section
And now it will be possible to select the organization from the menu.
One important think to keep in mind is that on the very first login with Github user are asked for permissions of interaction with their Github account and Organizations. Organization Admins should Grant access to the organizations to make sure this functionality works as expected