If you are logged in to ExO but you cannot see the units you are enrolled in, it could be because the unit has not started yet and the lecturer or course coordinator has not 'opened' the unit up and made it visible to students. This is common, as units are continually worked on and improved between semesters. Check with your lecturer or the Head of School to confirm if this is the reason. They may also be able to tell you when you can expect the unit to be open to view.
If your unit has already begun and you are unable to see the unit in ExO, please contact the lecturer or Head of School, or log a ticket with the 'Help Centre' and someone will investigate the issue for you.