Hello! I started my application on June 1st and choose Colorado right away. On June 29, they sent me an email saying thank you for the application, even though I hadn't sent it in yet. They followed up with an email saying that it was a mistake. I fully sent in my application on July 3rd. I then waited a month for a payment email. It wasn't until August 17th that I realized they may have sent the payment information in the mistake email. I went back and looked and sure enough, they did! (I must have been freaking out about them saying they got my app, that I completely over read it). I sent in the payment on the 17th and then got my invitation on the 22nd.
If you got the mistake email, go back to it and pay your fine! If not, then I would call the school.
Good luck!