Linux – How to Install Linux Subsystem for Windows

I'm encountering a problem while trying to install Linux subsystem on my Windows 10 machine.

I'm following the procedure, found on this URL. I've tried to launch the following command (in Powershell, as an administrator), but I get an error message:

dism.exe /online /enable-feature /featurename:VirtualMachinePlatform /all /norestart

Deployment Image Servicing and Management tool
Version: 10.0.16299.15

Image Version: 10.0.16299.1127


Error: 0x800f080c

Feature name VirtualMachinePlatform is unknown.
A Windows feature name was not recognized.
Use the /Get-Features option to find the name of the feature in the image and try the command again.

The DISM log file can be found at C:\WINDOWS\Logs\DISM\dism.log

I've tried to use the Get-Feature option, but I don't know how to get this to work:

dism.exe /online /GET-feature /featurename:VirtualMachinePlatform
...
Error: 87

The get-feature option is unknown.

My DISM logfile looks as follows (only the first error lines):

2020-12-17 15:44:08, Error                 DISM   DISM Package Manager: PID=9820 TID=9400 Failed to get the Update through CBS. - CDISMPackage::Internal_OpenFeature(hr:0x800f080c)
2020-12-17 15:44:08, Error                 DISM   DISM Package Manager: PID=9820 TID=9400 Failed to get the underlying CBS Feature - CDISMPackage::OpenFeature(hr:0x800f080c)
2020-12-17 15:44:08, Error                 DISM   DISM Package Manager: PID=9820 Feature name VirtualMachinePlatform is unknown. - CPackageManagerCLIHandler::Private_GetFeaturesFromCommandLine(hr:0x800f080c)
2020-12-17 15:44:08, Error                 DISM   DISM Package Manager: PID=9820 TID=9400 Unknown features were specified on the command-line. - CPackageManagerCLIHandler::Private_GetFeaturesFromCommandLine(hr:0x800f080c)
2020-12-17 15:44:08, Error                 DISM   DISM Package Manager: PID=9820 TID=9400 Failed to get the Feature List from the command line. - CPackageManagerCLIHandler::Private_ProcessFeatureChange(hr:0x800f080c)
2020-12-17 15:44:08, Error                 DISM   DISM Package Manager: PID=9820 TID=9400 Failed while processing command enable-feature. - CPackageManagerCLIHandler::ExecuteCmdLine(hr:0x800f080c)

Does anybody know how to proceed now?
Thanks in advance