This video will show you how to change the creative from landscape orientation to portrait orientation in order to be displayed in a vertical mode on your digital signage display device.
However, changing a creative in a playlist to be in portrait orientation is not enough for displaying vertical playlists. You need the Android operating system to be rotated to portrait orientation mode which can be done by flashing your Android device with a custom firmware or using an application that can save you the firmware flashing for screen rotating.