I checked the %ENV with the diagnostic script it shows REMOTE_USER is there and has the correct value. However it still does not capture the value for my script.

  my $user = $ENV{"REMOTE_USER"}; should be picking up the username if the diagnostic script shows that it's there. When you set $user yourself, are you using exactly the same username that the diagnostic script prints?

Were this me, I would do

print $query->header(),
      $query->start_html (-title=>"Volunteer List Form ($user)",
      ...
[download]

to verify what I'm getting. Then I'd focus on the query logic.