I just went and checked it out. I’m not an author here, but here’s my impression so far from the perspective of an Envato buyer who is also a production music musician. I offer tracks independently for a different type of market, so you guys aren’t my competition.
I noticed several former top selling authors and some current, but not their most popular money making songs. I had heard a number of top sellers mentioning in the forum that they had not been invited, so it doesn’t appear that’s how they selected who would be invited. As for the quality, it’s not the best material. But, nothing I listened to was bad. It’s good quality.
That being said, I suspect that a lot of Elements users will find these tracks good enough to not use AJ as much, if at all. Time will tell, but there are at least 6011 songs there at the moment and I’m pretty sure most Elements members will find something they can use there without needing to search AJ.
If you are looking for the licensing policies a buyer will see, those are here:
Otherwise, I think authors are by invitation only.