Here is a successful attempt using unsecure Windows File Explorer FTP. I'm showing this to prove that there is a user Windows account amorris
I'll follow up with an unsuccessful using Filezilla
2017-06-14 16:15:15,299 DEBUG FTP.UserCommand [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] User XYZ.com\amorris available - password required
2017-06-14 16:15:15,299 DEBUG FTP.FTPConnection [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] Processed command USER XYZ.com\amorris
2017-06-14 16:15:15,299 DEBUG FTP.FTPConnection [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] CMD< 331 Password required for XYZ.com\amorris
2017-06-14 16:15:15,299 DEBUG FTP.FTPSession [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] setting state to AwaitPassword
2017-06-14 16:15:15,299 DEBUG FTP.FTPConnection [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] OnSend: Response 18
2017-06-14 16:15:15,299 DEBUG FTP.FTPConnection [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] BeginSend: Response 18
2017-06-14 16:15:15,299 DEBUG FTP.FTPConnection [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] Obscuring user password
2017-06-14 16:15:15,299 DEBUG FTP.FTPConnection [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] CMD> PASS ********
2017-06-14 16:15:15,299 DEBUG Core.User [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] Authenticating Windows user XYZ.com\AMorris
2017-06-14 16:15:15,299 DEBUG Core.WindowsImpersonation [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] Searching domain XYZ.com for user AMorris
2017-06-14 16:15:15,408 INFO Core.WindowsImpersonation [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] Windows Interactive logon succeeded for XYZ.com\AMorris
2017-06-14 16:15:15,408 INFO Core.WindowsImpersonation [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] Using Windows identity domain\AMorris
2017-06-14 16:15:15,408 DEBUG Core.ImpersonationContext [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] Impersonation begin -> 'domain\AMorris'
2017-06-14 16:15:15,408 DEBUG Core.PlugInManager [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] Created plug-in WindowsFolder with class EnterpriseDT.Net.FtpServer.FileSystem.Windows.FolderAdapter
2017-06-14 16:15:15,424 DEBUG Core.ImpersonationContext [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] Impersonation end -> 'NT AUTHORITY\SYSTEM'
2017-06-14 16:15:15,424 INFO Core.UserSession [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] XYZ.com\AMorris logged into Default Site with protocol FTP on y.y.y.y:21 from x.x.x.x:53274
2017-06-14 16:15:15,424 DEBUG Core.User [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] ActivateSizeWatchers()
2017-06-14 16:15:15,424 DEBUG FTP.PassCommand [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] User XYZ.com\AMorris logged in (Key=70b8f43a-9512-4b18-83f9-1ca92b560491)
2017-06-14 16:15:15,424 DEBUG FTP.FTPConnection [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] Processed command PASS ********
2017-06-14 16:15:15,424 DEBUG FTP.FTPConnection [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] CMD< 230 User XYZ.com\AMorris logged in.
2017-06-14 16:15:15,424 DEBUG FTP.FTPSession [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] setting state to AwaitCommand
2017-06-14 16:15:15,424 DEBUG FTP.FTPConnection [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] BeginSend: Response 19
2017-06-14 16:15:15,424 DEBUG FTP.FTPConnection [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] OnSend: Response 19
2017-06-14 16:15:15,424 DEBUG FTP.FTPConnection [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] CMD> opts utf8 on
2017-06-14 16:15:15,424 DEBUG Core.ImpersonationContext [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] Impersonation begin -> 'domain\AMorris'
2017-06-14 16:15:15,424 DEBUG FTP.OptsCommand [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] Forcing encoding to UTF8
2017-06-14 16:15:15,424 DEBUG Core.ImpersonationContext [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] Impersonation end -> 'NT AUTHORITY\SYSTEM'
2017-06-14 16:15:15,424 DEBUG FTP.FTPConnection [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] Processed command opts utf8 on
2017-06-14 16:15:15,424 DEBUG FTP.FTPConnection [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] CMD< 200 UFT8 enabled.
2017-06-14 16:15:15,424 DEBUG FTP.FTPSession [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] setting state to AwaitCommand
2017-06-14 16:15:15,424 DEBUG FTP.FTPConnection [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] BeginSend: Response 20
2017-06-14 16:15:15,424 DEBUG FTP.FTPConnection [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] OnSend: Response 20
2017-06-14 16:15:15,424 DEBUG FTP.FTPConnection [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] CMD> syst
2017-06-14 16:15:15,424 DEBUG Core.ImpersonationContext [Session.10:Default Site:XYZ.com\AMorris:x.x.x.x] Impersonation begin -> 'domain\AMorris'