After having installed the Add-on from the Atlassian Marketplace, you first need to do some general configuration.
Please head to the General configuration and select the Slack for Confluence menu entry on the left side under the Configuration category.
There, you need to paste a Slack Incoming Webhook URL into the form. To generate the URL, just click on the “Create a new Incoming Webhook in Slack” link and set up a new Incoming Webhook within Slack.
Make sure to use a public channel for the Webhook – e.g. #general – the exact channel and other settings like bot icon and name in the Incoming Webhook don’t matter, as all of them get overridden within Slack for Confluence.
Proceed by copying the Webhook URL from Slack and paste it into the form in the Slack for Confluence configuration.
You can also modify the Bot’s name, icon, and the appearance of the notifications within Slack in the Global Configuration.
To try out sending notifications, specify one or more channels under Global notifications. Note that all updates throughout the entire Confluence installation will be propagated with notifications to those channels and users, so it might not be reasonable to use this with big Confluence installations. You can configure more fine-grained notifications in the scope of a Space, Page, or User as described below.