Is there a reason you don't want to use either of your existing accounts? There' no need to create a YouTube account just for your TiVo.
On your PC you need to log into whatever YouTube account you want to use on your TiVo. Either one of your existing accounts, or create a new one. Once you're logged in on your PC with the account that you want to use then you should be able to go to the page the app is telling you to and enter the code which will link that account with the YouTobe app on your TiVo.