Are you displaying digital signage on an UltraWide monitor, video wall or any other nonstandard proportion device? Then, custom resolution is what you need.
This option is part of the layout section in your campaign editor. If you don’t know yet how to create different screen layouts, adding different divisions and changing from landscape to portrait mode, check this tutorial.
Learn how to set custom resolution:
TIP: Keep in mind that depending on your video wall configuration, the image might get distorted. Always add content which matches the screen resolution, like this one: