The plugin "works," in that it shows an activity feed. However, specifying your meetup group name and URL does not affect which meetups' activities are shown. The plugin does not offer any option to limit the feed to ONLY activities from a particular group.
This issue makes the plugin unusable for me. I am an organizer of one group and a member of several others and I wanted to use this plugin for the website of the group I organize. I don't want to show activity for all the other groups I'm in as well.
If this issue were fixed I think it'd be an excellent plugin.