i'm getting error CS0246: in unity editor,I'm getting error CS0246: in Unity Editor

Hi guys, hope all be good, So i'm a using Unity 2018.1 version and i'm trying to setup proGrids package, after i install it form package manager i get error here is : "cannot use because is it not in c# 4.0 language specification" in Editor. So when i changed the scripting runtime form .net 3.5 to 4 than i get a new error here is "packages.unity.com/com.unity.settings-manager@1.0.2/Editor/UserSettingsRepository.cs(61,16): error CS0246: The type or namespace name `SettingsScope' could not be found. Are you missing an assembly reference?"
So how i can fix this error and can use a progrid safely i need help please . Thanks for all.