Well, ghost-CLI isn't listed among the prerequisites, but okay, I've installed ghost-CLI. And I installed an instance of ghost. And I tried moving all of the ghost-on-github-pages files to that directory with that Ghost installation already in it.
./install never asked me for any info, including that url it's supposed to ask me for. No matter what I do, it says "Working directory is not a recognisable Ghost installation." Why is this happening?