Between .NET 3.5 and .NET 7 the System.Drawing
now has to be installed as a separate NuGet package.
Are you downloading the package from the NuGet site? If you are then you don't need to - there's a built in package manager in Visual Studio. Right click your project, go to "Manage NuGet packages...", click on the "Browse" tab at the top and then search for "System.Drawing.Common". The first option should be a package published by Microsoft. Click that and then "Install" on the right hand side.