Condition: hold ticket receipts with confirmed seats departing in 72 or 144 hours - Need help.

Greetings - I will disembarkation at Shanghai Port International Cruise terminal, stay in Shanghai for two days, then fly back to Australia via Kuala-Lumpur. One of the conditions for 144 hour Visa free is "Holding air tickets with confirmed seats". I already bought tickets, but I don't now what does "Confirmed seat" mean.
Does it mean the seat number in the fuselage, which I only have when I enter the airport and get the boarding pass, or I can get it (seat number) when I check in online 24 hours before the flight.
Hope you can help me with this headache issue.
Thanks and have a good day.