Alex's answer is correct, but AFAIK the AdfinX Real-Time COM library is a desktop API. What this is means is that your application will be tied to the desktop. And it will require an installation of Eikon on that desktop.
If your aim is to create some kind of thingy that will run on a server and send contributions from there then you are better off using something like RFA .NET edition.
Without having tried AdfinX Real-Time COM Library I'm guessing it is a lot simpler to use than the server side APIs simply because the config/setup is already done for you and these desktop APIs aren't normally made for high performance so a lot of complexity can be removed from API. The server side APIs are are lot more versatile but also have a steeper learning curve. Your choice.