Download and install Visual Studio 2019.
During installation, select the Mobile development with .NET workload.
If you already have Visual Studio 2019, you can add the Mobile development with .NET workload:
Download and install Visual Studio 2019 for Mac.
During installation, ensure the Android + Xamarin.Forms and iOS + Xamarin.Forms platforms are selected.
If you want, you can also Pair to Mac for Xamarin.iOS development.
An iOS emulator is included in Visual Studio 2019 for Mac and was installed during the previous step.