Could you please suggest us.
path: 'WebViewer/lib', // path to the PDFTron 'lib' folder on your server
licenseKey: 'Insert commercial license key here after purchase',
pdftronServer: 'http://XXXXX:9090/', // comment this out to do client-side only
The path is just a static folder directory where PDFTron would load its library files, You can make a directory inside your server folder, and use that directory for lib, or alternatively you can use a Amazon s3 storage as well, which is mentioned in PDFWebviewer documentation.