The way that you propose to install Discourse is one that no one here is familiar with. If something goes wrong, you won’t be able to get help here. It might just work just fine, forever, but thus far, no one here seems to have heard of it.
If you are coming here for advice and the question is “how can I install Discourse and have Ghost be the DiscourseConnect (SSO) server for my community” the answer is to perform a standard install on a subdomain on a separate server from Ghost. There are some other topics about running mulitple sites on a single server.
Using a subfolder is considerably more complicated than keeping the site on its own subdomain, so it’s not recommended unless you have a really good reason (and improved SSO is no longer believed to be a good reason) and also have some expertise in setting up Discourse. Many fewer sites use a subfolder, so many things, especially some theme components, are not well tested in that configuration, so they too might break in ways that they would not if you just used a subdomain.