There is no bus from the airport to Hangzhou at that time. So, if you want get to Hangzhou that day, you should get to Shanghai South Railway Station to catch trains to Hangzhou. You may miss the last bullet train leaving from Shanghai Railway Station at 8:10pm, so you can catch K trains in the south Railway Station which are also fast, two hours to Hangzhou. Last train leaves at 23:57 to Hangzhou East Railway Station, which is about 8km from the hotel near the West Lake. Suggest you take a taxi.