Download and install Visual Studio Community Edition When running the installer it will ask which components are required, the only one you have to choose for Jellyfin development is .NET Desktop Development: The install will be close to 6GB so may take a while. While it is installing you can install FFMpeg, this isn’t technically required to get Jellyfin to run whilst you develop, for example if you are only working on a metadata plugin you won’t need the server to transcode anything, but if you do need make sure items play then it is best to install FFMpeg.