Slack Even Subscription.
The Request URL has to point to your Appmixer backend server. The rest of the URL /services/appmixer/slack/events has to remain like this. Your Appmixer backend server has to be running before you enter the URL. Slack will immediately try to connect to that URL.
Then you need to subscribe to
Don't forget to hit Save Changes:
You can now use the appmixer.slack.list.NewChannelMessageRT component in a flow.