I interviewed with Midwestern University in Downer's Grove (IL) last year at the time, and I will assume that it will be the same in Arizona for you because it is the same school.
Due to COVID-19, I don't know what has changed but will give you my take on what to expect. A schedule of the interview day was provided to us in a folder along with other information about the program as you first walk in. They briefly spend the interview day in the beginning talking about the program, financial aid, etc. to start it off like many schools and their interviews. Just like the other person that mentioned this above, there was an essay that they have you complete first before your interview, which is handwritten and gave 15-30 minutes for us to complete (can't remember the exact time). The essay had two prompts, and you only need to choose one to talk about depending on whichever you are most comfortable with.
After that, they split your group up into two halves (there were around 10-15 students for our interview day in total). One half does the interview first, and the other gets a tour of the school by current physical therapy students that attend, along with answering any specific questions you have. They walk you through buildings and show you some rooms to give you an idea of what their lifestyle is like there, along with equipment and what classrooms look like. After that, the group that interviewed first goes on the tour. The one on the tour first then does their interview. I can tell you from experience that Midwestern University was also one of my first interviews and did not know what to expect. This made it a bit stressful, but I promise you that it is not bad at all.
I work as an aide with three other physical therapists who graduated from Midwestern University, and they all told me about their experience and was the exact same as what they described for the interview day. They described it more of as a conversation and barely felt like an interview, which made it less tense. The interview itself was maybe 10-15 minutes long depending on how much you want to talk about with their questions. You can expect them to ask you to introduce and talk about yourself as the very first thing, like many other schools. This is your chance to talk about what makes you unique as a person and for them to determine if you would be a good fit for their school. Try not to make your whole life story and introduction revolve around physical therapy, they already know this from your personal statement and will ask you questions about this later on anyways. Use this chance to talk about things like leadership, hobbies you have, life experiences, etc. for them to get to know you as a person and what you're like. Additional questions they asked me focused on what kind of experiences I have with physical therapy, such as shadowing. They also asked me about what qualities I consider to be important for a physical therapist. Overall, it flowed very well like a normal conversation and was not stressful. The interviewers were very friendly and done by faculty. Try to convince them like I said though, on why you are a good fit for their school. Each school is different on what they look for in an applicant, so do some research about the school to aid with this. Make sure that you sound natural and that you're not just memorizing answers to interview questions, be a human. They don't want robots as physical therapists!
As always, don't just focus on the questions they asked me because they will likely not be the same other than introducing yourself. Walk in confidently, and you both will do great!
Good luck!
