Spatie PDF/Jpg converter - PHP Fatal error: Class 'Imagick' not found in ...

Hi all, I'm not able to use spatie converter in my server:

<?php

namespace App\Http\Controllers\Documents;

use Spatie\PdfToImage\Pdf as JPG;

class converter
{
    static function PdfToJpg($pdf_path){
        //conversione del pdf in jpg
        self::mylog("Funzione PdfToJpg ... converto il file ".public_path($pdf_path));
        $jpgs=[];
        $img = new JPG(public_path($pdf_path));
        self::mylog("Ho istanziato il convertitore spatie");
        $pages=$img->getNumberOfPages();
        $jpgs=[];
        for($i=1;$i <= $pages;$i++){
            $img->setPage($i)->saveImage(public_path($pdf_path.$i.'.jpg'));
            self::mylog("Ho salvato il jpeg");
            $jpgs[]=$pdf_path.$i.'.jpg';
        }
        return $jpgs;
    }
}

thi is my class that crashes when it does: $img = new JPG(public_path($pdf_path));

In /var/log/apache2/error.log I can rread this error:

PHP Fatal error:  Class 'Imagick' not found in /home/ottaviane/Sviluppo/WebDocuments/app/Http/Controllers/Documents/converter.php on line 16, referer: https://webdocuments.mydomain.it

I installed spatie with: composer require spatie/pdf-to-image

What appen? Can you help me please? Bye bye.