If you want to play in the NCAA D1 or D2 then you must register with the NCAA Eligibility Center… this can be done online. There is a fee to do this online per the NCAA.
Here is the link: NCAA ELIGIBILITY CENTER
If you don’t register with the NCAA Eligibility center then you cannot play any NCAA D1 nor D2 sport… it’s that simple.
College coaches will absolutely ask is a player is registered with the eligibility center. If a player is not, then the college coach will tell the player to register ASAP. To put it differently, you are not “recruitable” until you register with the eligibility center.
None of the above applies to NAIA schools nor Junior Colleges.