Can I purchase Maglev ticket when I arrive at the Pudong Airport, or should I purchase in advance?

1. Just buy the metro tickets when you landing at the airport.
2. According to your arrival time, you don't need to take the train. There are several direct coaches at the airport that can take you to Hangzhou. The bus schedules after 16:00 are 16:40, 17:25, 18:00, 19:00, 20:00 and 21:00. The bus tickets can be purchased at the airport.
3. If you still wanna take the bullet train, Hongqiao Railway Station is a better choice because it has more schedules (though the south station is relatively closer to PVG). The last train to Hangzhou is at 21:37. TravelChinaGuide provides ticket online booking service. If interested, their contact information is bookingtravelchinaguide.com.
4. From PVG to Hongqiao Railway Station, you can take direct airport shuttle bus line 1. Or take SMT to Longyang Road Station. Then transfer to subway line 2 to Hongqiao Railway Station. You can choose the way you like. :)