Assuming the ticket was created in your Finance ticket app, that notification should have gone out through our mail sender per your organization's outbound mail configuration. What was the exact date/time of the post that said it notified them?
Also, did they check their spam/junk mail folders to be sure whether the email was not shunted there?
I do see that they have the notified setting to true for all group members and they all have access to it, so there's no reason the notification shouldn't have been sent. I can check the mail logs though if I know the date/time of that feed post.
Sr Support Consultant, CS