The install docs also gained the piece that was missing: email

Sign-in is a magic link, so a new server can't sign anyone in until it can send mail -- and nothing documented how. New page: email.md -- the four SMTP settings for sending through a provider you already use, or Amazon SES with a link to Scott Hanson's setup walkthrough. It's a step in the install checklist now, along with a link to the questions thread -- if something in the install isn't working or isn't explained, that's where to say so.