There should be one file with an .exe extension , "Pumpkins_Client.exe" Just double click it and you're good to go!
Ps: If the PC asks for a confirmation before running (sometimes happens when the author of the software is unknown to your PC) just click in more details and "run anyway", that's like saying to your PC "hey you may not know this author and don't want to run the exe but I do know it and I know It is safe to run"