Syncplify.me Server! also supports authentication for Active Directory groups. If you have several people who must share the same FTP(S)/SFTP server configuration, then putting them in the same AD group may greatly simplify your configuration.
Besides it own internal user database, Syncplify.me Server! can authenticate users against the Windows user database and/or the Active Directory.
This article explains how to authenticate users against the Active Directory. A different article explains how to use the Windows (local) user database.