System Configuration
System Configuration pages can be accessed by users with Super Admin permission. Those are site-wide global settings.
Site Configuration (Open Source version only)
Site Configuration allows you to configure correct website URL for your FeatureHub app, for example this is a prerequisite for enabling Slack integration.
Slack Configuration
This is a global Slack setup page, which will help you to connect FeatureHub organisation (or deployed instance of Open Source version) with Slack. See more details on Slack integration page.
Encryption needs to be enabled and configured to allow for Slack to be enabled. Slack will not appear if and encryption key is not configured.