I should mention the possibility that "Mad 27" is not related to the main game and might be a different project. Advising them to check the official website or community forums for any related content would be helpful. Also, if they're looking for a portable version of a game, that typically involves running it on a laptop without installation, which can be done via portable apps or emulators if necessary.
This usually suggests the file has been compressed or formatted to play easily on mobile devices or via a USB drive without needing complex codecs. Where to Find Hiyori Shirai's "MAD-27" glory quest mad 27 hiyori shirai avi 1 3 gb portable