I visited last week. How to get access to the Slack channel?

[Philip J. Reed]

Seems like this Google group is dead but perhaps someone still subscribed will see this.

Last week I attended a meeting of your group where the Slack channel was mentioned as available to attendees. I see it linked on Meetup. However my attempts to join on Slack's site haven't succeeded. Is this group by invitation only? 

Regards,

Philip