No need to apologize. Apps like this "appear" to be legitimate, but if you read down the description, you'll see the following:
Legal notice:uSound doesn't store links to music or store music in its servers.
It isn't our responsibility the contents that can be downloaded with our application.
Please, only download music that you got the right to copy."
This is clearly NOT a legitimate music service. The RIAA even defines downloading of music from alternate sources, even if you have the original CD as pirating. You can "rip" your own original CDs, and make as many copies for your own use as you choose, but the moment it's downloaded from somewhere else, and you haven't paid for it, legally, it's not "legal".