You are missing the audio files that go with them like wav or wma.
Just do a search for Free Loops, get the loops you need and the loop info like key, tempo or beats and enter that info for each file this will make a bt6 file for each file, these stores the info you entered.
If you have all your files on C:\bb don't worry about the RealTracks folder options.

Download them here: Nature_Sounds_Loops.zip Percussion_Loops.zip