Hi zalophus,
Thanks for your inquiry.
It is important to note that the availability of channels and the requirements for accessing them can vary depending on the service provider and the device being used. If you have an HBO subscription through your Xfinity service, you should be able to access HBO content on your Roku using your Xfinity or HBO login credentials.
However, if you encounter an error or issues upon logging in, we recommend checking with your Xfinity service provider for more information on their available channels and their compatibility with Roku.
Please let us know if you have any further questions.
Regards,
Nimfa