Root is by passing the locks and barriers that were built into your device. For most people who root their devices it's like unlocking the full potential of the device they have bought and gives them control similar to the control most experience on a PC or Laptop. Freedom to install anything they want, play with all of the settings the manufacturer or carrier has locked down or slowed down, change OS, and on and on.
As for the app it looks like the dev has two versions. One with limited capabilities that works with your device under lockdown and one with more capabilities that are only available if you have rooted your device. You have to be able to freely do the things this app is offering in order for it to be able to do the things you are asking.