It works like this:
A bunch of us pool our money together and form a Pitt Booster NIL collective.
We "sign" players and pay them X amount. Lets say 100K/year for their NIL rights.
We go out and tell ABC Dentist, XYZ Restaurant, etc we are offering them the following athlete to be a spokesman for their business. Since college athletes arent worth anywhere near what we are paying them, our NIL collective will take a big loss but that's the point. We gave the kid 100K and only recouped 20K from different appearances and commercials and what have you.