[5] Refers to what qualifies as a connecting flight. For example, if you arrive in transit on 3 January then the departure flight of your transit must be before 06:00 on 4 January for it to qualify as a connecting flight under these rules. Obviously, you can only access the lounge before the qualifying connecting flight. It would be absurd to argue that your guest could stay until 6am the next day, which is potentially more than 24 hours after your departure. That clearly isn't the intent of the rules.