Array from C++ to C#

I am trying to pass a double array (its actually a std::vector, but converted at transfer) from a c++ dll into a c# script (unity). Using the approach outlined here https://stackoverflow.com/a/31418775.

I can successfully get the size of the array printing on my console in unity however I am not able to use "CoTaskMemAlloc" to allocate memory for the array since I am using Xcode and it doesnt seem to have COM.

For a little more background this array is part of a control for a GUI, c++ creates it and the user edits with the c# GUI - so the plan is to be able to pass the array back to c++ when it has been edited.

C++ code
extern "C" ABA_API void getArray(long* len, double **data){
    *len = delArray.size();
    auto size = (*len)*sizeof(double);
    *data = static_cast<double*>(CoTaskMemAlloc(size));
    memcpy(*data, delArray.data(), size);
}

C# code 
[DllImport("AudioPluginSpecDelay")]
private static extern void getArray (out int length,[MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 2)] out double[] array);

int theSize;
double[] theArray;
getArray(out theSize, out theArray);

If I leave out the code concerning the array, the int passes just fine. So I beleive the method to be the right one, its just getting around the lack of CoTaskMemAlloc.