Paying Provider Directly from FSA Account?

I have an FSA account through work. The administrator is Wex. I see a therapist quarterly via Telehealth. In the past I have paid the him out of pocket via check (he doesn't have Stripe or Venmo or Zelle or anything like that, he's very old school) and then he provides me a receipt that I submit to Wex on their website for reimbursement.

I was just on the Wex website reviewing a recent charge and I saw an option whereby I can apparently send a payment to a provider directly from my account. I was curious so I clicked through to see the steps. All it asks is the provider's name and address and an uploaded receipt. It does not - I repeat, DOES NOT - ask for the provider's banking information.

I am having trouble understanding how this works. If my above-mentioned therapist were to send me a receipt ahead of time after an appointment and I used this "send a payment" function through Wex, how would he get his money without me supplying his banking information?

I feel like I need to reiterate that at no point during this "send a payment" function on the Wex website does Wex ask me to provide banking details for my therapist. I can't imagine Wex is sending him a paper check? Or are they? How does this even work?