The UserIsolationMode property defines the isolation type desired on the corresponding FTP site.
If UserIsolationMode is set to 0, there is no user isolation. This setting is the default and is backwards-compatible.
If the property is set to 1, a client authenticates using local or domain accounts, then is sent to a folder under the root matching the user name. This setting is known as "Isolated (Locally)", and supports users who do not want to use Active Directory (AD).
If the property is set to 2, user isolation is dependent on Active Directory. This setting is known as "Isolated (Active Directory)" and is primarily of use to Internet service providers (ISPs) and other customers who want to set up large numbers of FTP accounts.