That is the name of a module inside XML-LibXML, which is the distribution. When you install XML::LibXML either way, you'll get XML::LibXML::Document, meaning it's already installed on your machine.

Question is, why don't perl see it. Since the name VMWare has been mentioned, I tend to assume you might be running it from a Virtual session inside your Fedora, which might not have this module installed. But there could be other reasons. More details on your environment might help.