Joining multiple monitors into one is not something MaxTo can do by itself, but most video card drivers support it.
This guide will therefore focus on how you do this for the three largest video card manufacturers.
Important note
To get this to work, all the monitors you combine will need to have the same resolution.
Do you want regions spanning multiple monitors?
This is the how-to guide for you. MaxTo's regions cannot span multiple monitors unless the video card driver tells Windows that they are really one larger monitor.
This how-to is also particularly relevant for anyone with an ultra-wide that is being driven using two video cables and a Picture-by-Picture (PBP) mode.
Please find your video card manufacturer in the list below and follow the instructions.