Welcome to the Roku Community, @AngelicaL!
Thanks for informing us about this. Rest assured that we'll help you add the Max app to your channel lineup.
Before we proceed, could you please confirm if you have the same Roku account linked to your other Roku device in which the Max app is visible? You may check it under Settings > System > About. We need to ensure you have the same Roku account linked to all of your Roku devices as this will mirror all the apps installed in one device to another.
We'll be looking forward to your update.
Best regards,
Carly
Carly Y.
Roku Community Moderator