Connecting to s7-plcsim

Hi, im trying to follow this tutorial but instead of using windows forms in visual studio i want to use unity (with visual studio) and get values from the plcsim. https://www.youtube.com/watch?v=cOMouM1R0AU

while it works fine just like this using windows forms. I cannot seem to make it work with unity. I get the error "are you missing a refrence?"

I read somewhere on google that i might have to import the reference .dll file, and when i tried that i get a COMExeption error. I dont know if thats what i need but any help is appreciated.