How to use PhpSpreadsheet without installation (like PHPExcel) : <p>According to the <a href="https://phpspreadsheet.readthedocs.io/en/develop/#installation" rel="noreferrer">PhpSpreadsheet Doc</a> it's neccessary to install it with composer. 
In my case I just have a webspace without Terminal but Plesk. Is it anyway possible to use PhpSpreadsheet, like it is with <a href="https://github.com/PHPOffice/PHPExcel/blob/1.8/install.txt" rel="noreferrer">PHPExcel</a> where you just have to place the files in any location?
What do I have to do to get it run? I found no further information how to with only FTP webserver access.</p>
