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Community Project is a C++ Plugin, all you need to do is to copy and paste the entire folder and you need to copy the entire Plugins folder inside your project folder. Your project need to be a C++ one. Once the copy and paste is finished, you right-click your project file (.uproject) and select “Generate Visual Studio project files” it will assemble your project including the plugin. Once you open your project double-clicking the .uproject file or via Launcher you will be asked to compile the plugin, which you will say yes.
It takes some time to understand the project parts and setup. I would recommend to get the original project and start to strip the elements you think you dont need and see the results to understand better (since it will start working already).
Several blueprints are based (derives from) classes in C++, so it is not possible in a easy way to make the whole project to work as blueprint only. The large gains using C++ directly in project comes from the buoyancy, which is CPU bound, and will execute really fast, while a pure blueprint counterpart would not (unless nativization was used nowadays, but didnt exist when the project started).
As for the type of water you need with Forward Rendering and MSAA, with some little changes in the various water materials we have inside the project you can use it with Forward Rendering and as for MSAA I didn’t try myself changing the Project settings, be my guest. My current line of work is focused on the deferred render.