Which program are you applying to? Which form are you using to apply? And where are you applying from? What’s the exact wording of the response you got from the university?
One “typically” does not need to be a current college student to apply for admission to a full Bachelor’s degree program. One does need to be a current college student to apply for admission as an exchange or visiting student.
However, depending on the country you are from, your high school curriculum may not be deemed equivalent to a Dutch high school diploma. In that case you WOULD need to show additional qualifications (e.g. 1-2 years of college) in addition to your high school degree in order to qualify for admission.
OP is from Indonesia, so according to that link would need to have completed two years of university [presumably in Indonesia] before applying to Amsterdam.