How much does a good score on ACT/SAT increase my chances whereas I can waive them?

“Many strong applicants will come from many countries. Part of the first step is to learn how you may be competitive- not just grades ad scores, but for the challenges of adapting to a US university. MIT may not be the right choice for you. We don’t know more about you.”
@lookingforward
first of all, thank you for the nice help!
My brother lives in the USA and he studied his Ph.D. at Columbia University.
What do you exactly mean by challenges of adapting to a US university? Could you please give me more information about?
Why do you think MIT isn’t a good fit for me? because its curriculum is so challenging? (My brother though doesn’t recommend it to me so much)
What kind of information do you want to know about me? I would be happy if you give me more advice.