Hard to explain succinctly, but see if this helps.
https://ncaaorg.s3.amazonaws.com/ch.../2018-19D1MWR_QualifierAllocationCriteria.pdf
Thanks, but that document was written for people like you who already understand quite a bit, not a beginner like me. Yet it did help me understand some of what was posted by others, such as the minimum 17 matches and .700 winning percentage against D-1 competition. Still not sure what is meant by "legs."