As you see in the above article and Air Asia's website, there is shuttle bus, but only one bus every day. As you arrive late at night, I don't think you can catch the bus. Taxis do not allow 5 adults, only 4 at most in one vehicle. Do not take taxi from Hangzhou airport to Shanghai by taxi. The fare is incredible, more expensive for you to stay one night in Hangzhou hotel for two rooms. As I know the ticket for Air Asia shuttle bus can be bought on the plane. You can ask before landing about the shuttle bus information.