I have this set up. It works. Details forthcoming. 

It’s pretty straightforward: 

1. New topic trigger
2. Slack channel message

We used the custom option to specify the category (group). My private group isn’t showing in the list of category options, but you can specify with the custom tab and use the ID# at the end of the group URL. I think support helped us troubleshoot this when we set it up 2 years ago. 

You’ll need separate Zaps for the reply and join requests.

For join requests, your trigger is going to be a Webhooks by Zapier app that subscribes to the group.MemberRequest webhook)

@DannyPancratz Thanks so much! 

I ran into one issue - the Zap is sending a Slack notification for a topic outside of the category (private group) I specified. Is this where you had to bring in inSided support? Do you see any other filters that might be helping your Zap?

@security_lion i often find that the test data from testing triggers pulls in any new topic (even when specifying a specific content type of category/group)

to address and test, you could post in that group to be the most recent post and then refresh the trigger in Zapier to get that a test data. 

As a safe guard I often add a filter step in between to only continue if it’s the right conditions (ex. category and/or content type)

For anyone who comes into this thread later, follow @DannyPancratz instructions. Thanks again @ddpancratz!

I added a filter as an additional step because my instance was pulling topics and replies from outside of the group. This filter seemed to work, though as you can see in the thread, you might only see the issue in your tests.

For this, you look at the URL of the private group and copy the name and the number of the group. It might look something like, “private-group-1”. Your filter should then say, Only continue if Topic URL contains private-group-1.