Not sure what part you are having trouble with but try this

#!/usr/bin/perl
use strict;
use warnings;
use File::stat;
use Text::CSV_XS;
my $csv = Text::CSV_XS->new(
  { binary => 1, eol => $/ }
);

my $ONE_DAY = 86400;
my $Foutput = "data0426-2.csv";
open my $out, ">", $Foutput or die "$!";

# create array of csv filenames in directory
my $dirname = "Daily_QoS_CPD_link";
unless (-d $dirname) { 
  die "Not able to open $dirname";
}
my @dir = glob "$dirname/*.csv";
   
# parse files modifed in past 24 hours  
foreach my $infile (@dir){
    
  my $age = time()-stat($infile)->mtime;
  if( $age < $ONE_DAY ){  
    open my $FH, "<", $infile or die "Could not open $infile : $!";
    while (my $row = $csv->getline($FH)) {
      if ( $row->[2] =~ /^(DROPPED-10|CALL_START|CALL_END)$/ ) {
        $csv->print($out, $row);
      }
    }
    close $FH;      
  }
}
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Works beautifully. I think I need to look up a few things to see how/why/what of them like using "glob" and "unless. Whew! Most of the components you have in your code are what I had in mine. I was close, but, alas...no cigar. (sad face) BUT->I'm learning!! Thank you so much for your assistance. I kinda like Perl, its very powerful.

glob does more or less the same thing as opendir /readdir, except that it is more practical: first, it's one line instead or two, second it removes pseudo-directories such as "." and ".." which you usually don't want to explore, and finally it returns a list of files with their path, so that you can open them without having to add the path.

unless does exactly what the English meaning of the word implies. It is essentially equivalent to if not. For example:

my $q = $c / $d unless $d == 0; # avoid division by zero error
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