I'm sure they would announce it online if it was sold out and you can print bought ticcets out from the website or show them from your phone.
You get the tickets at the box office. Just make sure you bring the card you paid for them with you and the conf. Either print it or on your phone
You just print your conformation that pops up after you pay for tickets online. And it should say if a movie is sold out. Or you can always give them a phone call.
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