The AWS SDK for .NET V3 has entered maintenance mode.
We recommend that you migrate to AWS SDK for .NET V4. For additional details and information on how to migrate, please refer to our maintenance mode announcement
Special considerations for Xamarin support
Xamarin projects (new and existing) must target .NET Standard 2.0. See .NET Standard 2.0
Support in Xamarin.Forms
Also see the information about Portable Class Library and Xamarin.