Redirect subdomain to different IP/folder

I was trying to redirect a subdomain ie billings.example.net to 1.2.3.4/billing. Well, from my experience I could access the 1.2.3.4 server and create a vhost pointing that the incoming of billings.example.net should be redirected to the 1.2.3.4/billing address. But, unfortunately, I don't have the access to the 1.2.3.4 server so I need to do something else.
So what should I do now? How can I resolve this error?

I think you want this configuration in the VirtualHost definition for billings.example.net:

ProxyPass        / https://1.2.3.4/billing/
ProxyPassReverse / https://1.2.3.4/billing/

Then any requests to billings.example.net/* will be transparently forwarded to 1.2.3.4/billing/*. You don't need admin access to 1.2.3.4 to set this up.