How to give file permissions to AzureAD user on windows 10?

Thanks to Arni on this thread for the answer:

You can try the following command line. After adding an ACL entry, the Security dialog will display the user and you can change the permissions there.

CACLS "C:\YourPath" /T /E /G AzureAD\FirstLast:C

My cheating way: Add the Azure user to a unique local group "net localgroup groupname domain\user /add" Then give local group permissions