Thank you very much. I have that link as well. Apparently it is mostly just about algebra. Yes our school is doing it. Seems not anyone have heard about this test.
Our school has entry tests for MX1 and Advanced as well. It is mostly to filter out unsuitable candidates to not overpopulate the MX1 Cohort however I was able to do the exam however I did not have the same stress as I was recommended regardless. You shouldn't worry about entry tests as they are aimed to test the bare minimum; your foundational skills. For our exam they tested mainly Algebra (Large component), Trigonometry (relatively small) and briefly functions which the 5.3 class covered. I would highly suggest you to hone your algebra skills rather than anything as that is most likely the biggest component that will be tested for entry since everything from Adv+ practically requires good algebraic manipulation.
I would just do algebra exercises from your textbooks, really get used to manipulating surds, fractions, cross-multiplication etc. Entry exams aren't supposed to be hard at all so if you're a decent student and you've paid attention, it should be pretty easy. Just ensure your algebra is up to date, the rest doesn't matter as much. All the best.