Notepad ++: CS script Error CS0009 for reading CoolProp.dll file

Question

Some background: I am a newbie to C# and programming in general. Utilizing notepad ++ for my script writer and compiling the program through the command prompt. I am using the CS-script plug in for building CS projects. I am a full time mechanical engineer and trying to utilize an open source alternative to Refprop which is CoolProp (https://github.com/CoolProp/CoolProp) for pulling fluid properties for refrigeration equipment sizing. Trying to develop tools for myself in component evaluation in design.

The problem: I have saved the CoolProp.dll file in the same location to the CS script that I am writing. The CS-Script has found the .dll file for reference but still outputs a CS0009 error. I have tried to trouble shoot the issue by looking through the CoolProp, CS-Script, and CS0009 error discussions on stack overflow. No luck...

Below is my source code (not much written because I am trying to troubleshoot this issue):

//css_args /ac
using System;
using CoolProp;

public class SystemTools.cs
{
    public static void Main()
    {
        double p;
        p = CoolProp.PropsSI("P", "T", 300, "D", 1, "Propane");
    }
}

Thanks for the help in advance everyone.