using C1.C1Zip;
using System.Net.Http;
using Windows.UI.Popups;

private async void LoadZipFile()
{
    // load file from the Web
    HttpClient client = new HttpClient();
    C1ZipFile zip = new C1ZipFile();
    try
    {
        // Download zip into byte array.
        var byteArray = await client.GetByteArrayAsync(new Uri("htt://yourfile.zip", UriKind.Absolute));

        // Write byte array to stream and open
        MemoryStream ms = new MemoryStream();
        ms.Write(byteArray, 0, byteArray.Length);
        zip.Open(ms);

        // Load entries into FlexGrid
        _flex.ItemsSource = zip.Entries;
    }
    catch (Exception ex)
    {
        var dialog = new MessageDialog(ex.Message);
        dialog.ShowAsync();
    }
}