Connect with FTP as user to user directory

I "Added a user to this server", with e-mail and FTP.

Defined "Subdirectory of server's home" as /home/domain_name/public_html/user_folder

Using the username.domain and the password, I should be able to log into his directory for him, right?

I have tried both www.domain.com and www.domain.com/user_folder as the hostname in FTP.

When I try to log into the Usermin for that user, I get
Failed to create /home/subsim//home/domain/public_html/user_folder/.usermin : No such file or directory

I checked my public_html directory for the domain and there is a folder called user_folder there for the FTP user.