Grav on Windows Server 2019

Dear all,

I am trying to install Grav on an a host service running Windows Server 2019 and Web Server Microsoft IIS 10 with support of ASP.NET | Open-source web framework for .NET Framework 3.5/4.8 PHP 7.4 Perl 5.26

The zip file has been unpacked in the /root/grav-admin directory but as soon as the browser goes to the right address as, the system generates the error:

Fatal error : Uncaught RuntimeException: Failed to save file D:/inetpub/webs/ in …

Asked to the hosting service support they answer only there are wrong right permissions to be fixed.

Do you have any idea of that?

Thank you