Xamarin.Auth Android project results in "Cannot find symbol" error for CustomTabs?

I am trying to implement the Xamarin.Auth library. After installing it in my client project I received a System.NotImplementedException:

System.NotImplementedException:

Portable Bait And Switch is nuget feature, so the package must be installed in all project.

Therefore, I installed the library in the Droid project as well. Once I did this, I started getting "Cannot find symbol" errors related to the CustomTabs control:

error: cannot find symbol
extends android.support.customtabs.CustomTabsCallback
symbol:   class CustomTabsCallback
location: package android.support.customtabs    Kpa.Mko.Mobile.Client.Droid
H:\...\obj\Debug\android\src\android\support\customtabs\CustomTabsClient_CustomTabsCallbackImpl.java

There are 6 of these errors in all, each one related to CustomTabs in some way.

We're using:

• Xamarin.Auth 1.3.2.5
• Xamarin.Forms 2.3.3.193
• Xamarin.Android.Support.v7.AppCompat 25.1.1
• Xamarin.Android.Support.v7.CardView 25.1.1
• Xamarin.Android.Support.v7.MediaRouter 25.1.1
• Xamarin.Android.Support.v7.RecyclerView 25.1.1

I've done some research on this problem in the forums, StackOverflow, and Google but none of the suggested fixes I'm seeing is solving my problem. I am completely confused as to what could be going on here. Am I missing the obvious?

Thanks!