I think what is important to understand is that rclone isn't a server. it can connect to a whole bunch of different servers, be they cloud or other types, but you can't get around that you need a server on one of the machines to acomplish this. You need an endpoint to connect to on one of the sides at least.
I'm not quite sure why you need rclone to move data via just two servers, but if you have control over both then why not just set up a normal network share? (a network share is technically a file-server). If you want to use rclone over that network share for whatever reason, you can use the "local" remote as Darth points out to connect to that location. You also have other options for servers like FTP, webdav ect. but a network share is probably the most efficient and compatible I would bet.