Perhaps you need to create the intermediate sub directories first.

#!/usr/binperl
use strict;
use CGI;
use CGI::Carp 'fatalsToBrowser'; # add this only during debugging
my $cgi = CGI->new();

my @nombre_archivos = ("NI","RP","RDZ","CRF");

my $archivos = $cgi->param("archivos"); # warning list context ?
my $inst     = $cgi->param("inst");
my $fecha    = $cgi->param("date1");
my ($anio,$mes,$dia)= unpack 'x2 a2 x a2 x a2',$fecha;
my $ymd = join '-',$anio,$mes,$dia;

my $upload_dir = "/var/www/html/public_html/";
for my $subdir ('rev',$inst,$ymd){
  $upload_dir .= $subdir.'/';
  unless (-d $upload_dir){
    mkdir $upload_dir, 0775 
      or die "Could not mkdir $upload_dir : $!";
  }
}

my $ind = 1;
my $filename = "$upload_dir/$ymd-$nombre_archivos[$ind]";
open UPLOADFILE, '>', $filename 
     or die "Could not open $filename : $!"; # add filename into error
+ message
print UPLOADFILE "Test";
close UPLOADFILE;
[download]

Update : Or alternatively use make_path using File::Path