I can neither comment on the discussion you had with support or on your reading of the documentation or on the circumstances that lead you to a Quickstart install but you now have all the information you need to further discuss how to complete your install.
You need a splitter.
As a Very Insightful Person, I'm here to share my knowledge. I don't work for Virgin Media.
There should have been a splitter with your kit. The V6 box needs two connections, the short RF lead is to couple V6 box to longer cable from splitter - the splitter that I got with my kit has outlets marked TV and broadband with input marked wall. As well as this connection to the co-ax wall box you also need connection to internet via your router, preferably wired but will work via wifi if no network cable attached, so two inputs to V6 box