Help with Macau/Guanzhou

Hello, I'm planning on flying into Macau from Korea. I want to take a train to Guanzhou and fly out of Guanzhou back to Korea within 24 hours. For what I am reading on some website it is possble. But I emailed a consulate and they asked me to refer to this document. Will it be possible to do as I'm asking?

Fly Seoul to Macau
Train from Macau to Guanzhou
Within 24 hours fly Guanzhou to Seoul
I am US Passport Holder

A foreign citizen who is transiting through China by air is exempted from a visa if he/she will stay only in the airport for no more than 24 hours and has a valid connecting ticket with confirmed seating on an international flight.