If you want to install the mod, you have to do:extract the redist folder from .rar file downloaded;move the redist folder to the folder of the game Amnesia - The Dark Descent;JOIN, then DO NOT REPLACE, the redist folder with the other redist folder already present in the folder of the game Amnesia - The Dark Descent.You will find the mod ''Breach'' in the custom_stories folder!
You need to extract the files in the .rar into the save folder. They should have the .sav suffix. Make sure you have a backup of your save folder before you overwrite any saves you already have. Just copy the folder to another location in case something goes wrong.
One reason you might opt to use Terminal is that it allows you to hide any file or folder on your Mac, which is a great way to avoid that sense of residual curiosity felt by others should they come across a password protected .rar on your desktop! To hide files, just: 59ce067264