Just act like you know what you are doing.

"Yea totally, I want to make a challenge for recognition." He nods and offers you a pad with something written on the screen, looks like a waver and you put your thumb print on the marked place without reading it. He nods and guides you into the gym, from the outside it looks like a one story square stone building about a city block on each edge. The gruff man leads you inside and down a number of flights of dark stairs into a large echoey arena space completely covered in smooth sand. The ceiling is low enough that you could probably touch it and it is hard to see the walls from where you stand in the gloom.

"looks like you don't have any badges, I'll send in your challenges. Leave before Brock shows up and you are disqualified." with that he leaves the room leaving you alone in the vast but somehow claustrophobic and oppressive room.