Intallation Error!! Help

Installing I am getting the following error:

Installation Error: System.UnauthorizedAccessException: Access to the path 'F:\Program Files (x86)\Steam\steamapps\common\FSX\SimObjects\Airplanes\PMDG 737-900NGX\aircraft.cfg' is denied.
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
   at System.IO.StreamWriter.CreateFile(String path, Boolean append, Boolean checkHost)
   at System.IO.StreamWriter..ctor(String path, Boolean append, Encoding encoding, Int32 bufferSize, Boolean checkHost)
   at System.IO.File.InternalWriteAllText(String path, String contents, Encoding encoding, Boolean checkHost)
   at System.IO.File.WriteAllText(String path, String contents, Encoding encoding)
   at a.ah.removeOlderPrecipitFX(String simPath)
   at a.ah.d()
   at VFXCentral.MainWindow.A(Object , DoWorkEventArgs )
   at System.ComponentModel.BackgroundWorker.OnDoWork(DoWorkEventArgs e)
   at System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument)

Can I get some help please!!!