Ok, so you went downstairs & talked to the lady in the center. She says 'Welcome to the Pokemon Wi-Fi Club! Would you like to use Nintendo Wi-Fi Connection?'. You select GO TO WI-FI CLUB & it'll proceed to ask you to save your game. Save the game & they'll allow you to enter.
A blue screen should pop up asking you to connect again, select yes, & from there you'll enter the room where I'm at.