cannot convert from 'string' to 'System.IO.Stream'

I am trying to use a purchased asset called DMMap. It works great for PC Builds, but when I try to target it to the Windows Store, I get a bunch of errors.

Here is an example of one. Any ideas on how to fix this? Thank you very much.

Assets\DMMap\Lib\Triangle.NET\Triangle\IO\TriangleWriter.cs(42,59): error CS1503: Argument 1: cannot convert from 'string' to 'System.IO.Stream'

Code (CSharp):

1.  
2. public static void WriteNodes(Mesh mesh, string filename)
3.         {
4.             using (StreamWriter writer = new StreamWriter(filename))
5.             {
6.                 TriangleWriter.WriteNodes(writer, mesh);
7.             }
8.         }