Run these commands on PowerShell with Admin Privilege;

# add FTP site
# -Name [any name you like]
# -IPAddress [listening IP address] (below is 0.0.0.0 (all))
# -Port [listening port]
PS C:\Users\Administrator> New-WebFtpSite -Name "FTPRoot" -IPAddress "*" -Port 21 

Name             ID   State      Physical Path                  Bindings
----             --   -----      -------------                  --------
FTPRoot          2    Started                                   ftp *:21:

# set physical folder that is used for FTP site
# example below, create a [FTPSite01] folder under the [C:\inetpub\ftproot] that is created by default and set it
PS C:\Users\Administrator> Set-ItemProperty "IIS:\Sites\FTPRoot" -Name physicalPath -Value 'C:\inetpub\ftproot' 

# set SSL/TLS setting (example below is allowing No SSL)
PS C:\Users\Administrator> Set-ItemProperty "IIS:\Sites\FTPRoot" -Name ftpServer.security.ssl.controlChannelPolicy -Value "SslAllow" 
PS C:\Users\Administrator> Set-ItemProperty "IIS:\Sites\FTPRoot" -Name ftpServer.security.ssl.dataChannelPolicy -Value "SslAllow" 

# set basic authentication
PS C:\Users\Administrator> Set-ItemProperty "IIS:\Sites\FTPRoot" -Name ftpServer.security.authentication.basicAuthentication.enabled -Value $true 

# set read and write authority to all local users
PS C:\Users\Administrator> Add-WebConfiguration "/system.ftpServer/security/authorization" -Location FTPRoot -PSPath IIS:\ -Value @{accessType="Allow";users="*";permissions="Read,Write"} 

# set user isolation
PS C:\Users\Administrator> Set-ItemProperty "IIS:\Sites\FTPRoot" -Name ftpServer.userIsolation.mode -Value "IsolateRootDirectoryOnly" 

# set external IP address (the one client computers can connect - completely optional, if there is no host firewall on your server)
PS C:\Users\Administrator> Set-ItemProperty "IIS:\Sites\FTPRoot" -Name ftpServer.firewallSupport.externalIp4Address -Value "10.0.0.101" 

# create the [LocalUser] folder under the Path you set as physical path of FTP site (it is needed on this setting)
# if Domain users, create [(FTP root)\(%UserDomain%)]
PS C:\Users\Administrator> mkdir C:\inetpub\ftproot\LocalUser 

    Directory: C:\inetpub\ftproot


Mode                LastWriteTime         Length Name
----                -------------         ------ ----
d-----         9/5/2019  10:19 PM                LocalUser

# restart FTP site
PS C:\Users\Administrator> Restart-WebItem -PSPath 'IIS:\Sites\FTPRoot' 

# create folders for each local user that each folder name is the same with thier username
# naming rule ⇒ [(FTP root)\LocalUser\(Username)] (example below is for [ariw] user)
PS C:\Users\Administrator> mkdir C:\inetpub\ftproot\LocalUser\ariw 
PS C:\Users\Administrator> icacls "C:\inetpub\ftproot\LocalUser\ariw" /grant "ariw:(OI)(CI)(F)" 
processed file: C:\inetpub\ftproot\LocalUser\ariw
Successfully processed 1 files; Failed processing 0 files