To set up you sign so that it plays content in portrait mode, you can change the Orientation in your Sign settings. To get to your Sign settings, you can click on your sign in your mangosigns.com dashboard.
Once you click on your sign, you will see an Edit option at the top of the page that you can click on.
Once you click on edit, you will be in the Sign settings page where you can change the orientation of the screen so that your content displays in portrait mode on your sign and the click Update Settings to save.
If you set your orientation as Portrait and the content is upside-down on your sign/tv, you can change the orientation to Portrait Reverse which will rotate it 180 degrees so that it has the correct orientation.
Troubleshooting:
If your screen is displaying the content really skinny in the middle of the screen with black borders on the sides, that likely means that your TV has a portrait setting enabled in the TV settings. You will want to disable this so that the TV is in normal landscape mode, then try rotating the orientation in the sign settings in your mangosigns.com dashboard.