Your computer should come pre-packaged with WinRAR or Zip Extraction capabilities? You should just be able to download it and extract it
I forget what the game is zipped as, but if its just zipped and not rarred, Then Winzip or whatever windows currently calls their zipper, should come with every genuine installation of windows, unless they stupidly changed it for windows 10. Winrar should not be, its a 3rd party computer, you can get it from rarlabs, If I recall the company right...