I'm not clear what you are trying to do but to create a PivotChart you first need to create a pivot table. Are you trying to create a bar chart of counts for browser types like this ?

#!/usr/bin/perl
use strict;
use Excel::Writer::XLSX;

my $strExcelFilename= 'chart.xlsx';
my $book = Excel::Writer::XLSX->new($strExcelFilename);
my $format = $book->add_format(); 

my $sheet1 = $book->add_worksheet('Data');
my @header = ('User ID','Browser'); 
for my $col(0..$#header){
  $sheet1->write(0,$col, $header[$col], $format);
}              
            
my $row = 1;
my %count=(); # browser count
while (<DATA>)  {
  chomp;
  next unless /\S/;
  my @f = split ';',$_;
  ++$count{$f[1]};
  $sheet1->write_row($row++,0, \@f);
}

# add summary chart
my $sheet2 = $book->add_worksheet('Summary');
$sheet2->write_row(0,0,['Browser','Count']);
$row = 1;
for (sort keys %count){
  $sheet2->write_row($row++,0,[$_,$count{$_}]);
}

my $chart = $book->add_chart( type => 'column', embedded => 1  );
$chart->add_series(
  name       => 'Count',    
  categories => '=Summary!$A$2:$A$'.$row,
  values     => '=Summary!$B$2:$B$'.$row,
);

$chart->set_title ( name => 'Results of sample analysis' );
$chart->set_x_axis( name => 'Browser' );
$chart->set_y_axis( name => 'Count of Computer'  );
$chart->set_style( 11 );

# add chart
$sheet2->insert_chart( 'E2', $chart,  25,  10 );
$book->close();

__DATA__
user1;Chrome
user2;IE11
user3;IE11
user4;Chrome
user5;Firefox
user6;IE11
user7;Safari
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