This site lists all of the academic eligibility requirements of the 16 core courses taken in high school. Learn more at https://www.ncaa.org/student-athletes/core-courses.
This site lists what students/parents need to do for each grade level of high school. It provided significant details, including when the students take the ACT or SAT in grade 11, you submit your scores to the NCAA using code 9999. Learn more at https://www.ncaa.org/student-athletes/play-division-i-sports.
The CollegeBoard has a comprehensive website that details NCAA Eligibility. They have established the NCAA Eligibility Center to prepare high school students to meet the eligibility to play Division I or II sports in college. An excellent place to begin is with the Frequently Asked Questions page. Learn more at https://professionals.collegeboard.org/guidance/prepare/athletes/ncaa-eligibility-basics.