I transferred from Incheon Airport with Korean Air and even though just 4 hours.

I am afraid that the layover is too short. The time is not enough to join in that bus tour.
You are advised to stay at the the airport. Maybe you can have a rest at the hotel or go shopping at the duty-free shops. :)

No, I will have 11 hours in PVG. I want to join city tour.

You plan to do a city tour during the layover, right? Well, the time is enough. Just apply for a staty permit and you can leave PVG. You may take maglev train to Longyang Road Station (about 8 minutes). Then, take metro line 2 to East Nanjing Road (about 15 minutes). Upon arrival, you can see the Bund, East Nanjing Road Pedestrian Street, Hungpu River, Oriental Pearl Tower, etc. Remember to return to PVG at least 2 hours prior to departure. May you have a nice trip! :)

The airport doesn't provide free trip for us??

No, there is no such free tour.
Beside the above way I mentioned, you can take Maglev Train + Metro and get to People's Square Station. It's the nearest and most convenient boarding site of the City Sightseeing Bus. The ticket fare is CNY 30 or CNY 50 per person.

Thank you so muchヽ(^。^)ノ