It's pretty clear from the article that he was paid ~5K USD to replicate a piece of work he'd already created twice before—bank notes arranged to demonstrate av

It's pretty clear from the article that he was paid ~5K USD to replicate a piece of work he'd already created twice before—bank notes arranged to demonstrate average annual income. The museum also gave him the money that would feature in this artwork, but it was not intended as a payment. He's been told he has to pay back that money, but not his artist's fee.