You cannot use a Google account as a YouTube channel. You need to create a YouTube channel, which is a Google service only, ON the Google account of choice. It is why you are being asked to create one. :) My advice is to use a computer and to log into YouTube with your Google account (the one you wish to use and which doesn't yet have a YouTube channel on it) and then click any of the YouTube channel only options like My Channel, upload or try to comment. This will prompt the site to ask you create a YouTube channel for your Google account.
Once you have picked the YouTube channel username and completed this step you can then try again with the device. Try a fresh log in though as this will prompt the device to see that the Google account you are logging in with/to now has its own YouTube channel.
Don't think of it as linking a YouTube account to a Google account- look at it as adding the YouTube "plugin" (correct term is service, like Picasa, Blogger etc) TO your Google account and you cannot go far wrong. ;)