Hello,
Sorry but unfortunately there's no good site to get more information about that; all information available is a mess. Sometimes we use this page:
https://msdn.microsoft.com/en-us/library/office/ff837519.aspx
Anyway, maybe we can help you to configure the conversion plugin based on LibreOffice.
After installing LibreOffice and set the values in phpdocxconfig.ini, please try doing a transformation from DOCX to PDF (without macros) using PHP CLI mode. An important point about config is setting:
path = "'C:\Program Files(x86)\LibreOffice5\program'"
this is with ' and adding program to the path. As the path to LibreOffice has spaces your server may need these single quotes.
Regards.