You didn't specify what model Roku you have. You show a Roku TV as one device, but they are all manufactured by different companies, so we can't suggest who to contact if it's a TV. I use HBO Max all the time on my Ultra 4800 with no issues.
The first step to try when a channel isn't working correctly is to remove the channel, reboot the Roku (don't skip this step, and for a Roku TV this isn't just turning it off and on), then install the channel again.
Roku Community Streaming Expert
Help others find this answer and click "Accept as Solution."
If you appreciate my answer, maybe give me a Kudo.
I am not a Roku employee, just another user.