Buses to Zhouzhuang can be found in many places in Shanghai. Your hotel is along Subway Line 8 and you can walk a bit south to Laoximen Station to Xizang South Road Station and change to Line 4 to Shanghai stadium. Find the tourism hub there and take buses to Zhouzhuang directly. Nanpu Bridge tourism hub also have the bus. Time from Shanghai Stadium: 7：00、8：30、9：05、10：00、10：55, back from Zhouzhuang at 16：00、16：30、17：00. Time here is just for your reference. It is changeable. Or you can get to Shanghai South Railway Station by subway Line 2 and find Bus Shangzhu Line to Qingpu and change bus to Zhouzhuang.