Hi @philip2505,
Welcome to the EE Community
If you have TNT Sports as part of your mobile plan and previously set it up with discovery+ you would use the exact same details you used to login to discovery+ to login to HBO Max.
Once you are logged in you should be able to move to the Sports section to view TNT Sports content, this link will take you directly to the sports content if logged in if you want to give it a try to see if you can view it.
When you say you are signed in HBO and then say its not recognising your discovery+ login, what do you mean? Are you signing in with a different account to HBO?
Alex
