If you want to reset a user password, you need to configure SMTP first. That way, when you request a password reset, this is sent to the mail of the user.
In order to help you, could you please let us know how did you configured SMTP?
You can create (or modify if it exists) the
/opt/bitnami/apps/testlink/htdocs/custom_config.inc.php file. In the following snippet you can see an example of configuration for gmail accounts:
$g_smtp_host = 'smtp.gmail.com';
$g_tl_admin_email = 'firstname.lastname@example.org';
$g_from_email = 'email@example.com';
$g_return_path_email = 'firstname.lastname@example.org';
$g_smtp_username = 'email@example.com';
$g_smtp_password = 'password';
$g_smtp_port = '587';
$g_smtp_connection_mode = 'tls';
Then, restart the services:
sudo /opt/bitnami/ctlscript.sh restart
Let us know if you find any issues with it.