The error message says:
Assets/Standard Assets/Effects/ImageEffects/EdgeDetectEffect.cs(7,33): error CS0246: The type or namespace name ImageEffectBase' could not be found. Are you missing UnityStandardAssets.ImageEffects’ using directive?
I’m not sure if the error message came because i downloaded the asset or because of something else, all i know is that i got the error message after i downloaded that asset.