What's supposed to happen after claiming my instance?

So, after putting in my instance name, piefed.zeromedia.vip, and my admin username, guynamedzero, what is supposed to happen? It said that I'd receive a message with an api key, or something along those lines, but I don't think I've received anything. Upon trying again, it tells me: There was an api error: You have already claimed this instance as this admin. Please use the PATCH method to reset your API key. What am I supposed to do from here?