Enable basic authentication in IIS

Only basic authentication is available for connecting SharePoint Rest Interface in vCenter Orchestrator. Then, I go to IIS Manager and enable basic authentication under SharePoint website. But, the authentication method does not work actually. 

However, it works fine when I disable windows authentication. For your reference, 

Reference Link: IIS Authentication Methods

PowerShell: Add-PSSnapin WebAdministration in Windows Server 2008

An error occurred when I execute Add-PSSnapin WebAdministration.

After Goggling, I discover that I forgot to install IIS 7.0 PowerShell Snap-in as the OS is Windows Server 2008. On the other hand, it is no need to install the snap-in if your OS is Windows Server 2008 R2.

Installing the IIS 7.0 PowerShell Snap-in