Open Jint solution correctly

I need to open the Jint solution downloaded from here : https://github.com/sebastienros/jint (i've downloaded the zip with all the files, later i decompressed them and then i try to open the solution's file using visual studio)

Visual Studio (both 2012 Express and 2013 Express) tell me that the main project is not compatibile, i have tried Microsoft Visual Studio Version Selector but still not working. Anybody can tell me why this happen and how i can open and view that solution with all its projects properly loaded?

Here a screen of my situation :

This project targets the Portable Framework. You might need to install the Windows Phone SDK or some other component depending on your version of Visual Studio. Please refer to this page for more details.