As said in documentation:
Web HTTP(S)/SOCKS proxies have different instructions and will not work with these steps, see Tor Browser Proxy Configuration.
Documentation might be broken due to changes by Tor Browser, which is developed by The Tor Project, not Whonix.
Fixing this might be difficult. Nobody here might know how to do that.
One option would be using the https://www.whonix.org/wiki/Free_Support_Principle, attempting to accomplish this on Debian first and contacting Tor support should there be any issues.