you can try extracting the downloaded file and manually installing the files. If extracting is possible then that is what you should do. I know for sure that the FG Support section patch can be extracted, so that might work as well.
I tried both these methods and it would not work for me. The valusoft one wont even detect I have Amnesia installed and thus wont run.
I downloaded the Amazon.com version of the game. as far as I can tell Amazon does not offer an update for there version and it dont seem updated as I dont see Justine anywhere in the menu system.
Never mind I actually figured out how to get it to work.
I just took all the files out of the redit folder and dropped it in the same folder as my amnesia.exe just like when adding in the map tools and such. Works just fine now.