Try to unzip the file again.
Check if your antivirus didin't delete any files
If you downloaded it from here then it's a false positive(false alarm). You can check on virustotal or you can try using other antivirus programs.
Does this happen on all the gamemodes ? Have you tried to change the keybinds?
The game is free to play. The price is only for donations. There is a button above the price to download without donating.
