Hi Deborah,
That’s not going to work so well with Discourse. With Google, as I understand it, inviting a group to a calendar invite is a shortcut to inviting all users in the group. All users receive independent invitations to the meeting, and can accept or ignore them as needed. With a Discourse group, Google treats the invite as going to a single user - the email address of the group - and cannot do the “special magic” to invite all users of the Discourse group as individuals. All users would see the meeting invite, but would not be a guest.
The meeting link received by all should still work, and depending on your organizations settings they may have access to the meeting, or they may end up in the waiting area requesting permission to join. In either case, they’ll need to add the meeting and all its details to their calendars manually.