I'm unable to add one project as a reference to another project because they target different platforms.
However, when I try to change the platform targets in my Xamarin Forms app, I get the following error
The project's targets cannot be changed. The selected targets require the project to opt-into NuGet 3.0 support, however, Visual Studio cannot automatically do this for you. Please uninstall all NuGet packages and try again.
How exactly do I "opt-into Nuget 3.0 support" to fix this? As far as I'm aware, everything is running at the latest versions.