As already stated just putting all 16 folders on a USB does enable me to open any of the RGT's as required.
Yes, the OS is different from other keyboards, but the Playlist organization isn't. Setting up a Yamaha playlist is the same regardless of the playlist.
As has been stated, when you move RGT's around, the Playlist loses the link to them.
You need to copy the entire unzipped folder, including all subfolders, exactly as structured in the zip file. On a Windows computer, I simply drag the top level folder to the root directory of the USB. Windows unzips everything, and copies all the files. Hopefully, it's a similar procedure on a Mac.
I have a video on how to set up Yamaha playlists (link in my signature).
Cheers,
Fred