It’s on the AIS portal on the bottom in the checklist it says the student is required to manage. It says the following on my son’s:
Complete Math Placement Exam at Texas A&M (required) Note: All freshmen must take the MPE (Engineering students must complete the exam by May 20, 2017).
From what I understand though, you can take it up to 3 times with a 2 week wait period in between each. I do believe you only have to have at least one try in before your NSC. If your score is 22 or above you can proceed to Calculus. If you click on MPE in the Howdy portal it has practice problems you can study prior to taking the online exam. My son was happy he looked at the practice questions because the test is algebra, geometry, trigonometry and pre-calculus and he had not done any of that in years.