Paramount Plus with Showtime

I have an Xfinity Account that says I have "Triple Play Includes Preferred+, Paramount+ with SHOWTIME, HD DVR Service, HD Technology Fee, Gigabit Extra Internet, Xfinity Unlimited Select, Netflix Standard (HD) Plan.". I have never had an Xfinity HD DVR but have been using TIVO with cable card for years. Just bought a Tivo Stream 4K and was wondering how can I get access to my Paramount+ with Showtime" app. Like many I have gone to the Paramount Plus web site but Xfinity is not listed as a provider. Please help.