It looks like the .exe is scuffed.
For those who don't know, since this game was made with RPG Maker VX Ace, what is an .exe file is actually a self-extracting archive, whose contents you should be able to extract manually by using an archive manager. I used 7-zip, and well, it does try to extract the files... while spewing out errors for every single one of them. Furthermore, most of them end up getting extracted as 0 Byte files.
So yeah, again, the .exe seems to be scuffed and doesn't extract files properly, and it is definitely a problem that you can't do much but wait for the author to fix. Something must have gone wrong during the creation of the archive file.