Australian student wanting to attend an American University

Hey there guys i hope you are all staying safe :) I am a 15 year old student in grade 10 currently studying in Sydney Australia in the 10th best school in the state for academics. I have always wanted to go to an American university and go on to pursue investment banking at a bulge bracket bank at Wall Street. I was wondering if someone could point me in the direction of what do to in terms of securing a place in a semi target university as practically i don't think i will make any target schools (ivy league, UC schools). I was thinking about UW-Madison but after research i found that getting into the business school as a freshman is somewhat impossible and would require me to attend their liberal arts school and then transfer to the business school. So could you recommend me some schools that i should research and if someone could shed some light on doing the SATs in Australia and if ATAR had any weightage on university applications. Thank you so much for your time :)