Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
Welcome to the wonderful world of AT&T's HBO confusion.
HBO Go is for cable/satellite subscribers and is tied to that subscription.
HBO Now (I think) is being replaced by HBO Max.
HBO Max is the new one, but there is currently no agreement with Roku or Amazon yet.
To be honest, don't subscribe through Roku or other third parties if possible. Subscribe directly with the various services. They get 100% of the money, and you are free to use whatever device you want.