72 hours transit permit Shanghai without reserved seat on departure flight

I‘m going to visit Shanghai next month for less than 3 days and will arrive by airplane from Seoul.

I already have a booking confirmation for an onward flight to Copenhagen within 72 hours.

This booking confirmation for economy class does not include a reserved seat yet, because online check-in starts 22 hours before departure.

Now my question:

Do I meet the requirements for a 72 h transit permit with just the flight booking confirmation or do I have to make a seat reservation in advance (which costs me an extra fee)?