Open unren.bat with a text editor. Search for lib\windows-i686 and replace it with lib\windows-x86_64. That will let you extract the assets at least. It comes up twice IIRC
I'm not sure what's going on with the replays and not being able to pick options. Some of the rpyc files are encoded in what I'm assuming is the new Renpy 7.4 standard and not even the dev version of Unren can decode them yet so I can't look at the code to see why it's happening.
I think they're releasing unlocked saves soon just like they did with the last update so I guess it's either actually play the game (lol) or wait. Sorry.