As far as I can figure, the ten minute ambience tracks, the ones that have been pre-layered with all sorts of sound, is already integrated with the Roll20 platform. Tabletop Audio SoundPad on the other hand is a service offered on the Tabletop Audio site that lets you layer from the ground up and do it live. So all you want is soft rain? Can do. Strong rain and quiet winds? Can do. Throw in a little ominous pulsing? Yup. Pack animal noises in the distance? Totally. I find that the SoundPad tracks for rain, wind, etc. to be way more versatile because they're just rain, or just wind rather than the specifically crafted character of the ten minute ambience tracks which are just too specific in setting and mood, and too keyed to popular genres, for me to use in my games.