matched with a couple and had no idea how any of it works

First time this has happened and I genuinely do not know the rules.

Matched with a couple yesterday. Nice profile, well written, clearly not a throwaway account. They have messaged, it was friendly, and I have been sitting on my hands since because I do not know what I am doing.

Basic things I do not know. Am I talking to one person or two? Is it odd to ask that? Do you meet both at once or is that a big jump? And is there something obvious I should be establishing early that I would not think of because I have only ever done this one to one?

Any advice from people who have been on either side of it.