This level only gives you 100 seconds! Play as Peach to get the stamp here.
From the beginning of the level, jump towards the camera to grab the first green star and land on a hidden cloud. With that out of the way, head forward past some rotating pizza blocks to reach a fountain. The rabbit hiding in the left bush will circle the fountain, so tap it or chase it down to get the second green star.
The switch to the left of the platforms ahead is only pressable by Princess Peach - hit it for the level stamp. From there, keep heading forward and enter the cloud to reach a sky area with the final green star. The flagpole is immediately to the right of where you land after leaving that area.