Create a map that can be clicked + highlighted in Unity

I would like to create something like Hearts of Iron and Plague inc that highlights the region or country when you click on a map.

Of course, I looked it up on UnityAnswers and others, but I don't understand it properly because it's written in English.

How can I make a map like the one above? Please be specific.

The Unity version is 5.0.0f4.