
The Xamarin Android SDK Manager is not compatible with Visual Studio 2015. Java Development Kit 8 (the JDK 9 is not supported yet inXamarin.Android).Xamarin for Visual Studio version 4.5.0 or later.

(I’ll suggest you to use the latest version 15.6) Visual Studio 2017 version 15.5 or later is required.

On the Add a New SDK dialog box, select Android from the Select a platform drop-down list. See the Choosing your SDK page to see how to choose the correct SDK for your use. To add an Android SDK to RAD Studio: Select Tools > Options > Environment Options > SDK Manager. As you know is very important to keep your system updated and this of course is valid for the Android SDK.You should alway use the lasted available Android components.The Official Xamarin Documentation is not very clear on how to configure properly the Android SDK, so here is what you should do to obtain the best from your Xamarin.Android projects.First of all you should really install the Xamarin Android SDK Manager instead of the classic SDK Manager.Probably the most important reason to do so is that since version 25.2.3 of the Android SDK Tools package, Google replaced the UI Manager with a command line utility. Ensure that you are importing the correct SDK.
