Docker and Spatie PdfToText error exit code: 127 - php

Question

I have this code:
Global $windows;
$libiary_path = "./pdftotext";
if($windows)
{
$libiary_path .= ".exe";
}
$text = (new Pdf($libiary_path))->setPdf($file_name)->text();
return $text;
On linux in VM it works. I switched an docker and I get this error:
Fatal error: Uncaught Spatie\PdfToText\Exceptions\CouldNotExtractText: The command "'./pdftotext' 'this.pdf' '-'" failed. Exit Code: 127(Command not found) Working directory: /var/www/html Output: ================ Error Output: ================ ./pdftotext: error while loading shared libraries: libfontconfig.so.1: cannot open shared object file: No such file or directory in /var/www/html/pdf-to-text-main/src/Pdf.php:73 Stack trace: #0 /var/www/html/get_data.php(18): Spatie\PdfToText\Pdf->text() #1 /var/www/html/get_data.php(59): parsePDF('this.pdf') #2 /var/www/html/get_data.php(69): GetDataFromPDF('this.pdf') #3 {main} thrown in /var/www/html/pdf-to-text-main/src/Pdf.php on line 73
Everything is there. Exactly the same set of files on the Ubuntu VM and lampp works, not on the Ubuntu docker. I'm a beginner and maybe I don't understand something, but I can't find the answer on the web. Perhaps this is some very basic mistake.