server requirements for subdomain multisite meaning of “install, URL, root…”

I am reading this page about server requirements for setting up a multisite network
https://codex.wordpress.org/Before_You_Create_A_Network#Server_Requirements

and it states:

“You cannot choose Sub-domain Install (for a domain-based network) in the following cases:
1. The WordPress URL contains a path, not just a domain. (That is, WordPress is not installed in a document root, or you are not using the URL of that document root.) …”

I am not completey up on WP lingo to understand this satisfactorily. Could someone unwrap it for me?
“document root” “contains a path” “using the URL” ?

From my dashboard, my site url is “site.org” and my wp url is “site.org/wordpress”… I assume that means it “has a path” so I can’t use subdomain install? (I can’t use path install because it is not a fresh install) Doesn’t that mean that multisite is out of my reach? It is possible to remedy this?

I ask, because earlier in that page it says:

“If you want to use a sub-domain install, you must install WordPress in the root of your webpath (i.e. domain.com) however it does not need to be installed in the root (i.e. /public_html/) if you choose to run WordPress from it’s own directory. ” (emphasis mine)

I don’t understand this AT ALL . Does “install WordPress” mean set my wp url to the root of the webpath (site.org), or the site url to site.org, but the wp url can be different? What do they mean by the two uses of root?

Just for reference: This question arose as a subquestion out of another more general query: https://wordpress.org/support/topic/advice-movingrearranging-site-and-wp-urls/#post-8335337

• This topic was modified 7 years, 6 months ago by icqolsecretary.