Running ghost docker under example.com/url

I am running 1 ghost docker successfully as my main blog. (basic, using sqlite) The URL is set as an argument.

I am trying to set up a second one up under example.com/url but this does not seem to work

Accessing the site under example.com/ulr I get a ‘Cannot GET /’ in my browser, this happens also happens when I try accessing it under IP number:port

I assumed this would be easy to set up but this does not seem possible.
I have tried many variations: not setting a url etc.
with setting a url I get the admin page but I can see no pages.
I searched here a bit but did not give me any idea’s, redirections or routing might help but no idea how.

Anyone having suggestions?

Regards,

Gerrit Kuilder