Reference assembly with file path

I use CodeDom / Reflection to compile a C # script from a file. My current code is:

string sourceCode = File.ReadAllText(item);
var compParms = new CompilerParameters
{
    GenerateExecutable = false,
    GenerateInMemory = true
};
var csProvider = new CSharpCodeProvider();
compParms.GenerateExecutable = false;


compParms.OutputAssembly = "agame/temp/dll/common_" + Guid.NewGuid().ToString() + ".dll";

compParms.ReferencedAssemblies.Add("System.Windows.Forms.dll");
compParms.ReferencedAssemblies.Add("System.dll");
compParms.ReferencedAssemblies.Add("System.Windows.Forms.dll");
compParms.ReferencedAssemblies.Add("System.IO.dll");

compParms.ReferencedAssemblies.Add("C:/Users/" + Environment.UserName + "/_ache/external_acs.dll");


compParms.GenerateInMemory = true;

CompilerResults compilerResults = csProvider.CompileAssemblyFromSource(compParms, sourceCode);


object typeInstance = compilerResults.CompiledAssembly.CreateInstance("SomeClass");

MethodInfo mi = typeInstance.GetType().GetMethod("Add42");
int methodOutput = (int)mi.Invoke(typeInstance, new object() { 1 });

MessageBox.Show(methodOutput.ToString());

The fourth error occurs ReferencedAssemblies.Add()Here I tried to refer to an external DLL.
My mistake was: "Failed to load file or assembly's .dll location" or any of its dependencies. The system can not find the specified file. "
I also tried to reference all the dependencies of the external DLL, as shown below:

compParms.ReferencedAssemblies.Add("C:/Users/" + Environment.UserName + "/_ache/external_acs.dll");

compParms.ReferencedAssemblies.Add("C:/Users/" + Environment.UserName + "/_ache/csfml-audio-2.dll");

compParms.ReferencedAssemblies.Add("C:/Users/" + Environment.UserName + "/_ache/csfml-graphics-2.dll");

compParms.ReferencedAssemblies.Add("C:/Users/" + Environment.UserName + "/_ache/csfml-network-2.dll");

compParms.ReferencedAssemblies.Add("C:/Users/" + Environment.UserName + "/_ache/csfml-system-2.dll");

compParms.ReferencedAssemblies.Add("C:/Users/" + Environment.UserName + "/_ache/csfml-window-2.dll");

compParms.ReferencedAssemblies.Add("C:/Users/" + Environment.UserName + "/_ache/libsndfile-1.dll");

compParms.ReferencedAssemblies.Add("C:/Users/" + Environment.UserName + "/_ache/openal32.dll");

compParms.ReferencedAssemblies.Add("C:/Users/" + Environment.UserName + "/_ache/Otter.dll");

compParms.ReferencedAssemblies.Add("C:/Users/" + Environment.UserName + "/_ache/sfmlnet-audio-2.dll");

compParms.ReferencedAssemblies.Add("C:/Users/" + Environment.UserName + "/_ache/sfmlnet-graphics-2.dll");

compParms.ReferencedAssemblies.Add("C:/Users/" + Environment.UserName + "/_ache/sfmlnet-system-2.dll");

compParms.ReferencedAssemblies.Add("C:/Users/" + Environment.UserName + "/_ache/sfmlnet-window-2.dll");

How do I reference the file path to an external DLL? If it's not possible to refer to it through the file path, is there any way to reference an external DLL at all? I use it to allow scripts in my custom C # game engine.
Help with this problem would be very grateful!