HBO max not allowing me in.

Hi bobmertzman, 

Welcome to Apple Support Communities. We see that you're having an issue logging into HBO Max on your Apple TV HD. We'd like to help with this!

Do you receive any error messages when you try to sign into this app? Are there any updates available for your Apple TV or your subscriptions? Do you see your HBO Max subscription listed under your Subscriptions? See or cancel your subscriptions

Are you having any issues with your Apple ID and password in other places? Are you able to sign in to your account through the Apple ID website? 

The following resource may help with your issue: 

If an app unexpectedly quits, stops responding, or won’t open

Hope that helps!

Something you can try.

Apple TV - Restart.     

Apple TV - Reset.