It's a copyright management firm. Some countries have government-sponsored monopolists for that. This looks like one of those.

The author of a song and the performers may not be the same (most obvious with covers). Most of the money collected by Agadu is presumably paid out to the authors/songwriters (or whoever they sold the rights to?), minus management fees. Whether the pay-out scheme is fair, may be another point of contention. Think about a live band playing covers by various authors in some bar: How is it tracked what they play, and how much should be given to each of the many different authors? I don't know how that works in Uruguay, but my country has a system of that sort.