Help realise download file from Dropbox folder on Visual Basic 2015

Public Async Function Download(destination As String, file As String) As Task(Of Boolean)
     Try
                If client Is Nothing Then Await GetAccessToken() ' <- if your client is not defined then define a new client here
                Using response = Await client.Files.DownloadAsync("/" + file.Replace("\", "/")).ConfigureAwait(False) ' paths use / seperators, 
                    Dim result = Await response.GetContentAsByteArrayAsync().ConfigureAwait(False) ' wait for download completion
                    System.IO.File.WriteAllBytes(destination, result) ' write to file system
                End Using
                Return True
            Catch ex As Exception
                MsgBox(ex.Message, MsgBoxStyle.Critical, "Error downloading")
                Return False
            End Try
end function