Xfinity Rewards

I received a phone call in an email today that I had won a rewards package through Xfinity. I was told that I needed to create a separate account at xfinityrewardswinners.com. I am trying to confirm whether or not this is an actual website and whether or not I really did win a prize. The website is asking for me to complete a notarized form in order to fill out the prize. That felt like a major red flag, so I wanted to confirm before I went any further.