login failed on roundcube

[behrouzbash]

Hi, I followed the guide below but could not login:
https://www.arubacloud.com/tutorial/how-to-configure-a-pop3-imap-mail-server-with-dovecot-on-ubuntu-18-04.aspx

user: [email protected]
pass: password

OR

user: john     --->  config.inc.php :  $config['username_domain'] = 'example.com';
pass: password

I proceeded with the following command, it will be logged on the terminal side:
"$ sudo telnet localhost 110"    -->   +OK Logged in.

But I do not log in to the link "http://example.com/roundcube" and view it with the following message
"Login Fail"

I want to log in to RundCube email on "http://example.com/roundcube".

Where does this problem come from?
Thanks!!!

[alec]

Roundcube is an IMAP client. Check Roundcube logs and IMAP related settings.