Slang: "To have a twenty on me"

So I was listening to a song (bülow – Own me), and there’s this one line that I can’t really understand. Which is "Got nothing but a twenty on me", and I can’t really understand what it’s supposed to really mean. You can do a quick google search for the full lyrics, but in context the verse is

Car chase, got the Devil on me

Can’t see, got nothing but a twenty on me, on me

Nothing ever comes for free

You can pay what you want

But you’re never gonna own me

Song is something about like the when guys try to flex their wealth on girls and chase them like this, but that she doesn’t really care about that stuff.

I understand the expression to have a twenty on someone – which means to know their location. But it makes no sense in this context. And it kinda drives me mad right now. My common sense would say that she’s just trying to say that she doesn’t have that much money, but doesn’t really care about it. Though I’m not at all sure about that – hence the question.

If it helps, she’s from a Canadian descent, raised in Berlin.