It is advertised on the marquee sign just outside but it’s very easy to miss. Once inside you will have to make your way to back to find the line. There is no fastpass but since it’s not listed anywhere I would not expect to long of a wait.
This is currently my favorite meet and greet, the little Groot is so cute, he can move and says the phrase “I am Groot” for all his responses. The Star-Lord will sign autographs but baby Groot can not. As of September 5th this meet and greet was still open.