Earlier quoted context omitted.
That excerpt isn't about their funding. The CPB funds (in part) public radio stations . Many of those public radio stations purchase NPR-produced content . (And from other similar providers like American Public Media (Marketplace), PRX (This American Life), etc.) NPR's customers can't afford NPR's offerings without said Federal funding, which is why NPR's particularly interested in it.
That funding page says 31% of NPR's revenue comes from programming fees from member stations. Some of the 8% "other revenues" and 5% "PRSS contract" sound like they may come from member stations too, so let's call it 40% total from member stations as a best guess. Member stations themselves receive 13% of their revenue from the CPB (8%) and "federal, state, and local governments" (5%). Let's call that piece about 10%…
That's like saying a federal employee who chooses to donate some of their income to NPR is giving them government funding.