Welcome to the Community Forum and thanks for your post. You need to register for both TV Anywhere (to watch live TV, access On Demand/Catch Up, and control your TiVo), as well as for Sky Sports/Sky Cinema.
It's great that you are able to watch Sky Sports via TV Anywhere services; you just need to register your device on the TV Anywhere platform now.
Go to anywhere.virginmedia.com and sign in as normal. Go to the On Now section and select Channel 4 to attempt streaming. Follow the prompts on the screen and this will register the device for you and streaming will then commence.