Adjusting sequence square frame size for large screen size
If you don't want your video to be up-scaled then you need to output at the native resolution of the screen. The physical size doesn't matter, what matters is the pixel dimensions.

However, if the footage is not shot at the native resolution (and I don't think there are many 14K cameras around) you're going to have to resize it to fit. Whether you do that in your edit, or use whatever mechanism the screen has for up-scaling footage depends on a couple of factors:


can the screen / playback device do its own interpolation, and if so how good is it?
do you have graphics etc that you want to be crisp? If you're relying on the resolution of the screen to display small graphic elements crisply then you'll want the video that you deliver to be as high resolution as possible.
can the playback device handle a 14K video stream? Filesize is going to be an issue unless the playback device is pretty fast, and decoding it is going to be taxing for even a powerful machine.


Best bet: ask whoever is in charge of the screen. For a screen that large there's going to be an AV person who knows what they're doing. Ask around until you find who can give you specs for what you have to deliver.