It can be problematic to open the game,especially after an update, as it is like a new game.
It sticking is indicative of some problem with either your system or theirs.
In order to get the update working, the old version has to be removed, and there be enough working space, preferably uncluttered, on your device.
Try getting rid of rubbish by clearing history ,cache.
A new update can take ages to load , its like starting from scratch, patience is needed as it says on the webpage.
The game has to load onto your device in order to play it, its loading there, even if you dont 'Download'.
Downloading the app is supposed to be better, but some players still have problems with this way of launching the game.