What you've probably done is downloaded the Zip files (which are actually in 2 folders) I seem to recall the other one is a text or read me folder..... and then put it on a memory stick and then to your SX900.....
So go back. Open the folder that you unzipped on your pc, and you'll see you've got 2 folders...that's why the keyboard can't read it.
You only want the Playlist folder.
You want THAT folder on your memory stick, otherwise your SX900 won't find it.
Hope that helps.
Keith