C# on raspberry Pi using third party native DLL (DllImport Interop)

General information for the business: Reading Caller Id integration.
Kind of development: Customization of existing program
Description of requirements/functionality: We have a raspberry Pi with Raspian installed on it. We can install Windows IOT if required.

We have a usb callerid device. This device came with an SDK. It basically needs one DLL (problem is that that AD101Device.dll is available in x86 and 64bit, there is no version for ARM processors, there is no source code available for this DLL project)

We have installed MonoDevelop on the raspberry pi. I have wrote he following console app. It compiles fine. However when it tries to execute this like AD101_InitDevice(0); it complains that MIssingDLL. In windows world we have DLLs in linux they are *.so files. I dont have the *.so file.

I want someone to get this c# program working a raspberry pi. If you can change it and get it to successfully execute i can test it with the raspberry pi. I can do changes myself once we can get this interop to work.

You can download the SDK: Here.
http://www.artech.com.tw/DownLoad/AD101_SDK_20111214.rar

I have attached my code in a TEXT file.
Specific technologies required: c#, .Net, Mono, Rasberry Pi
Extra notes: