With absolutely no code, not even pseudo code to go on, it is hard to say, but I assume by...

how to keep the count of how many times the word appears on EACH URL

You really mean each PAGE referenced by each URL, no?

I mean, what is the problem with

my $wordcount;
loop_over_each_url {;
  search_through_each_page_content {;
    $wordcount++ (everytime_word_match);
  }
}
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