Have you tried turning your phone to landscape? Sometimes that works....or sideload it to a Chromecast or firestick if you have one.
Try to get the “Set Orientation” App
sometimes a set orientation app will help correct that... keyword is sometimes but I'd say it works more often than not.
Have you got a phone connect to the screen via cable?
If not then you will need to find the APK for Android TV not Android.
How did you install this app? it doesn't work outside iraq😅
Which phone are you using? Se if there's a "desktop mode"option. I have a Huawei P30 pro and when I connect the phone to the tv via WiFi or mhl cable, I have 2 options "phone mode" which is a screen mirror or "desktop mode" that shows a Windows like home screen.
Edit: You can also try to enable "auto rotation" on your phone and try to put the phone in landscape mode to see if the mirroring reflects that
rotate your tv, jk.