Hello,
As the path to LibreOffice include blank spaces, please wrap it with single quotes:
path = "'C:\Program Files (x86)\LibreOffice 5\program\soffice.exe"'
We also recommend you to follow the steps explained on:
https://www.phpdocx.com/documentation/conversion-plugin/debugging-libreoffice
to debug it. Maybe there's some rw access to the target folder.
Regards.