Plug-in version 3.20.11 installation failed

Further to my earlier question, the printer was finally discovered . However, Step 2 of HP Device Manager - Setup couldn't go further because:
1. unable to receive key from keyserver
2. The device you are trying to setup requires a binary plug-in. Some functionalities may not work as expected without plug-ins. Please run 'hp-plugin' as normal user to install plug-ins."
3. Accepted Licence Agreement but Plugin installation failed "error: Python gobject/dbus may be not installed"

Sending a document to print returned with a problem processing print error. Similarly, a test page cannot be printed either.
Any help to get it printing again would be much appreciated.

Thanks in advance