how to debug the xamarin android application in the android telepone version 8.1.0 in visual studio

hi help me please, I am trying to debug my xamarin android application on my android phone version 8.1.0 but I have an error message "xamarin android does not support the execution of the version previous "
i am using visual studio 2017 I downloaded the API 27 for Android 8.1.0 BUT I still have the same error, I even created an emulator with the API but visual studio 2017 does not support this. thank you in advance