Transfer Portal and Eligibility?

@kendall-rogers can you help me understand the NAIA eligibility standard and how it's different from D1?  They're are a number of guys in the portal who seem to be out of eligibility but it sounds like they can still play one more year if the transfer to an NAIA school??

I think an example of that would be Grant Garza of Tarleton, but I'm not sure how it all works.