I don't think many people on AN would've done this interview... but I did do an interview for architecture at Monash and I've done plenty of job interviews to sort of give very vague, general advice which may help you nonetheless.
Preparation before the interview
Read the interview offer notice very carefully. Consider the following:
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Does it say it'll be a formal affair or an informal shindig? This'll affect the clothes you'll wear. Of course, formal - wear good business attire; informal - wear smart casual (e.g. don't rock up in your favourite ripped jeans).
Does it say to be there 15 minutes early or nothing about time except the exact interview time? I'd always be cautious and be around the vicinity at least 10-15 minutes early regardless. Best to leave a good first impression.
How far away is it from you? Will you have to allocate extra time to be there? What can you do nearby if you arrive too early? This is especially painful if you'll be taking PT and it doesn't come often. Personally, I'd allocate myself to be ready by the second last ride and try to take that. If in any case that something happens to that second last bus/ whatever (touch wood that this doesn't happen), then at least you have the last one to get there by. I go against this rule if said interview is early in the morning and ensure I have a ride ready to go well before the interview.
If you're one who feels it necessary, will you wear make up and if so, what look? If not, what hairstyle (facial and/or on scalp) do you want to go with and what types of skin care do you need to do beforehand? How long will this all take? You know your skin care and morning routines better than anyone, so you'll know if you take an hour or 5 minutes to get ready. Hair, skin, make up and general hygiene will need to have allocated time. Be realistic.
Have you researched RMIT and their Music Industry course briefly? You should know at least RMIT's values vaguely, what the Music Industry's course map looks like and probably what the course will entail. You don't need to know much about this, but at least do your 15 mins of research and figure out the gist of each of these. Anything you can't find online can be asked at the end of the interview.
During the interview
Questions that are likely to pop up include:
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What's your motivations for doing this course?
What sorts of experiences have you had in the area? It's completely okay to not have much related. Just say that your hobbies have included X, Y and Z activities related to it.
What do you know about RMIT or the course already? This is usually more of a job interview question and unlikely to come up but do a little research in case.
What would you like to learn in Music Industry?
What sort of career aspirations do you have? Make this related to the course, even if it's vague.
And it usually ends with: Do you have any questions for us? (I get this one all the time.) Best answer for this situation is anything you're curious about. Do students usually come to campus on weekends? What sort of ATAR range do successful students have? What sorts of programs or scholarships does RMIT offer? How many hours do students usually work part time while doing this course/ Can I work part time during this course? What do graduates in Music Industry usually do after their courses? All very valid questions to ask.
Hope that helps.