Well I can't speak for the organisers, I'm just someone who attends. But they have proved that they are a conference for the same dates for the previous three

Well I can't speak for the organisers, I'm just someone who attends. But they have proved that they are a conference for the same dates for the previous three years. And the implication is that Paypal are asking for more documentation than previous years ("the documentation you are asking for this year...").