Authentication problem

Hello guys. I'm new here so I hope I'm in correct section to ask my question. I have AWS Linux Instance with Sentora 1.0.3 installed on it. Everything works perfect except ftp issues. I can connect to ftp with filezilla as sftp://hostname and my local usename/pwd, default ubuntu and root users are working like it supposed to. But when I create ftp user for domain, for example zadmin_user, filezilla can't connect to it with ftp/sftp protocol. Problem is like that:

Status: Connecting to 52.32.24.99...
Response: fzSftp started, protocol_version=8
Command: open "zadmin_user@xx.xx.xx.xx" 22
Command: Pass: **********
Error: Authentication failed.
Error: Critical error: Could not connect to server

I also want to mention that when I connect to server with SSH and ftp with "ftp localhost" command, it connects perfectly with that user I created:

root@blablabla:~# ftp localhost

Connected to localhost.
220 ProFTPD 1.3.5rc3 Server (Sentora FTP Server) [::1]
Name (localhost:root): zadmin_user
331 Password required for zadmin_user
Password:
230 User zadmin_user logged in
Remote system type is UNIX.
Using binary mode to transfer files.

I want to ask some questions:

1) How can I solve connection problem permanently? I don't want to configure some files each time after I create ftp user

2) How can I completely disable sftp connectivity in proftpd? I want all users to connect with unsecure ftp (currently I can't connect to ftp server at filezilla even with ubuntu or root users with ftp, but I can with sftp)

Thanks for attention and sorry for noob questions. Will wait for your reply