How to Create Top-Down Map of custom unreal engine scene?

I've created a custom scene in unreal editor 4.23 and have been following the mathworks guide shown in the link below.

https://uk.mathworks.com/help/driving/ug/create-top-down-map-of-unreal-engine-scene.html

The issue I am having is that I've created the screenshot of the map and do not know how to find the limits of the x and y for the image size.

I also don't know how to find the world x and y co-ordinates in the unreal editor scene.

Any advice is much appreciated.