The plugin is downloaded by integrating it into the Maven build process. The plugin may also be downloaded from its artifact repository, but since downloading does not resolve its dependencies, this approach is of little use.
This export creates an HTML site from the Enterprise Architect model stored in an EAP file. This is the same report that can also be created using the Enterprise Architect's GUI. But the plugin allows to integrate the generation process into the project's build process.
This export allows to create single images of your Enterprise Architect packages (i.e. diagrams) with their GUID as file name. Since the GUID of the diagram does not change, this is a perfect way to export your diagrams to be referenced from your documentation.