I have some questions about the CUNY Assessment Test in Mathematics

I am exempt from the Math assessment exam based on my High School Regents score. However, the following is stated in the CUNY website: "all new students - whether or not they are math proficient - are required to take the CUNY Assessment Test in Mathematics. Test results will be used to place students in the appropriate mathematics course at their college".

Since I am exempt from the CUNY Assessment Test in Mathematics, when and how can I schedule an appointment for the Placement exam? How do these two exams differ, and what else do I need to know before I can register for classes? Thanks.