You can achieve the same effect by changing weather settings:
Use cloudy sky weather (Select weather preset = 1) and click reload selected preset parameters in weather preset.
Now change parameters of weather:
CloudsHardness = 8
CloudsShadowSize = 0.22
CloudsShadowSoft = 2.0
If you need the hard effect on edges then change CloudsHardness to bigger value 
Alternative solution: Dropbox - File Deleted
Copy this preset to your project “Content\FastStylizedProceduralSky\WeatherPresets/WP_Stylized” and use according to documentation
I will add this stylization as new preset in the next version of the package, but can’t tell you when it will be because I’m still working on “time of day” presets.