I suggest you could try to modify the C:\inetpub\sites\Khadamatresan\Contents folder's permission to allow IUSR and IIS/yourapplicationpoolname to read and write file.
More details, you could refer to below steps:
1.Make sure you use the application pool advanced setting's identity is applicationpoolidentity

2.Right click the C:\inetpub\sites\Khadamatresan\Contents folder and select property.
3.Click the scruity and edit button.

4.If IUSR and your application pool name doesn't show in the window. I suggest you could
Click the add button and type in IUSR and IIS AppPool\.


5.Modify the permission to enable the full control
