Robinhood's Pay for Order Flow

My understanding is that they're able to offer this sort of brokerage service basically for free. If it's actually what you're writing a sense that they're selling all of their orders, it's called pay for order flow. So like the retail traders put in their orders and then they sell them to Citadel and Citadel fills them or not. And so when you go on Robinhood and you basically make that order, like you are creating the product for Robinhood to then sell to someone like Citadel,. which is your order is now the product that they are selling.