Hello! If UE4 project has C++ parts (that might be also plugin as here), it needs to be compiled. You should install Visual Studio (i use 2015, Community Edition, I guess that it was called). You will need it sooner or later, and - you need it now 
Now, important: i am also not a programmer, and I jumped into UE4 because it has visual Blueprints. I am bad at math, programming, I don’t have that kind of brain. But - believe me, VS is not that scary :)) You just need: common sense, logic, web searching, dedication. Not necessarily in that order.
So, basic steps here will be: right click on project file, and “generate VS files”. It will make SLN file. That will open in Visual Studio, when you have it in system. Then - “build solution”, pray. If it gives error(s) - use those common sense and search ingredients I mentioned