I suppose that your test application is a .NET Core app and you are trying to run it in a Debug or Release configuration. Despite that you are copying the Telerik.NetworkConnections*.dll-s in the application directory, the default behavior of .NET Core CLR is to load the dll-s from %USERPROFILE%\.nuget\packages\ directory.
If you publish your application, then you should be able to run it.
However, if you want to be able run your application in a Debug or Release configuration without publishing you will have to add the <CopyLocalLockFileAssemblies>true</CopyLocalLockFileAssemblies> property in your csproj file.
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