Thank you for you answer ! I can finally have the good end. :) And I just don't find the endind file when I download the game. Isn't it supposed to be there ?
The ending guide is a separate file from the game itself. When you go to the download page for the game there should be three options: the PC build of the game, the MacOS build of the game, and "Ending Guide [Chapter 1.5].pdf", and that last one is the thing you need to download for the ending guide