You have your CREDENTIALS setup so that you require 3 pieces of information to authenticate (authen_username, authen_domain, authen_password). But then in the DBI Driver, you are using __CREDENTIAL_2__ as the password, even though it is number 3 in your list. If you remove the 'authen_domain' entry, it should start to work.

Also, since DBIx::UserDB has it's own method for testing authentication, it might be easier to use that method through a callback, instead of the DBI driver. That way if DBIx::UserDB ever changes the DB structure, your code will still work.

use Digest::MD5 qw(md5_hex);

DistroPrsRls->authen->config(
  DRIVER => [ 'Generic', sub {
    my $username = shift; # credential 1
    my $password = shift; # credential 2
    if ($userdb->user_login($username, md5_hex($password)) {
        return $username;
    }
    return;
  } ],
  STORE => 'Session',
  POST_LOGIN_RUNMODE => 'login_welcome',
  POST_LOGIN_CALLBACK => \&update_login_date,
  CREDENTIALS => [ 'authen_username', 'authen_password' ],
  LOGIN_SESSION_TIMEOUT => {
    IDLE_FOR => '5m',
    EVERY    => '1h'
  },
);
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