I interpreted it as a deal/con on Quinn's part. I think Quinn has a deal with Burke where he basically "cooks the books" to give free tuition to her girls in exchange for their services. The money the girls bring in from other clients, Quinn takes and tells them that money is how she's paying their tuition, when it's actually just for Quinn, probably to help fund the drug business she's also running.
The fact that, through all of this, Quinn never seems to have enough money means she's not turning any actual profit off her scheme(s), which just points to Riona being right all along: Quinn's not as smart as she thinks she is.
This is one thing that really bothers me: at this point, is Quinn still planning on trying to get Maya into her "business"? Because if so then she is, to quote Riona, "a fucking idiot". Every indication Maya has given to Quinn is that she's not the sort of girl who will do that. Even telling her about it could potentially jeopardize their entire business. I get that Quinn gets off on manipulating people, but she has to realize there are limits.
Either way, the Maya/free tuition subplot really has nowhere to go as far as I can tell, unless DPC decides to completely ignore everything written to this point and have her start turning tricks, which would be total bullshit.