I have xfinity and get Netflix, prime and HBO Max. However, when I try to open them with Roku, I am asked for my user name and password.
As far as I know Xfinity does not have any bundle with Netflix, Prime or HBO Max. You can add HBO to your Xfinity cable TV plan. Netflix requires an active account and subscription to view content. Prime works off your Amazon account. If you pay for HBO through Xfinity you can log into the HBO Max app with your Xfinity credentials. Select "login in with TV provider". If you are paying for Netflix through Comcast then log into Comcast using your Comcast credentials.
https://www.xfinity.com/support/articles/netflix-billing-through-comcast
For a Netflix plan through Comcast, start here: Xfinity/Netflix FAQ
DBDukes
Roku Community Streaming Expert
Note: I am not a Roku employee.
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