So I downloaded the 21GB game, pressed PLAY button and it crashed. So I figured out maybe I can repair it! Well, it does not repair, it simply download the [censored] 21GB game again.

Also it shows that it was unable to download manifest or something..

I didnt face that problem. Sound disheartening. Are you certain the downloaded completed? Did you try the basic stuff, restart PC, restart client. I had mine crash at start when using Ventrilo, maybe an other software is messing it up?