A problem to connect to my Website by FTP

Hello,

I have a problem in my website guyperl.altervista.org
when trying to connect i get an error message:

Fatal error: Cannot redeclare get_cli_args() (previously declared in /membri/guyperl/wp-admin/includes/class-wp-importer.php:283) in /membri/guyperl/wp-admin/includes/class-wp-importer.php on line 334
There has been a critical error on your website.

so i was trying to connect by ftp and fix the plugin error,
but i can not connect by ftp (filezilla) and i get an error message,
even after i disabled my firewall and antivirus.

maybe my FTP service is not activated?
please help me connect by ftp to fix this problem!

thanks
Guy Perl (guyperl@gmail.com)

host: ftp.guyperl.altervista.org
server number: #467
username: guyperl
password: my password
port: 21

Command: USER guyperl
Response: 331 User guyperl OK. Password required
Command: PASS ************
Response: 530 Authentication failed. Your nickname must be lower case and your host ftp.yournickname.altervista.org , go to https://en.altervista.org to recover your password. If you have a Blog remember to activate FTP service.
Error: Critical error: Could not connect to server

Hello,
If you have an alterBlog account, you have to enable the FTP connection from Tools -> FTP. To resolve the problem, you should repair the blog from here.

Bye!

Thank You very Much, it Worked :=):