I purchased HBO Max for six months through the HBO Max website. But the HBO Max channel on Roku thinks I'm not a subscriber and so keeps asking me to get a trial of HBO Max. How can I tell Roku that I already have a Max account -- or does the channel simply not work unless I buy it through Roku?
Try to start watching something on the HBO MAX app. Before it starts to play it should give you two choices: "SUBSCRIBE NOW" and "SIGN IN". At least that's what happens here.