First check that the option to save hand histories in the William Hill poker client is enabled.
Settings -> System -> [x] Store Hand History Locally
If this was disabled play at least one hand without PokerTracker 4 so the hand history folder gets created on your computer. If you cannot see your C:\Users\Gábor\AppData directory in Windows then you will need to
enable the option to show hidden folders. If William Hill is not saving your hands there check these locations instead for your hand history folder:
C:\Poker\William Hill Poker
C:\Program Files (x86)\William Hill Poker