Gigatine

Greetings everyone ! Like I said in the title I've got a problem with Grisaia's installation. I already had the game but because of a bug I uninstalled it. When I tried to install the game once more Bootmenu doesn't work. After several hours of search I came to the conclusion that I'm missing a folder. Specifically the folder named "frontwing". Whenever I try to install the game this folder is missing. Can someone help me ? I would be very grateful.