Are you talking about Telerik's UI for Xamarin ZipLibrary assembly? You will need to use the Zip assembly delivered with UI for Xamarin because it is compatible with .NET Standard. The other Document Processing Library versions are not yet compatible with .NET Core.
Find the instructions here https://docs.telerik.com/devtools/xamarin/controls/ziplibrary/overview
and here's a screenshot of the assembly's location in the UI for Xamarin installation folder:
If you're asking about a general Xamarin.Forms / WinForms library, I recommend posting the question on StackOverflow or Xamarin Forums to get general Xamarin development assistance.
Lance | Tech Support Engineer, Sr.
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items