This article explains how to activate the Outreach integration. You need the same admin on both platforms (Postal & Outreach) to enable the integration. Integration only works for users with licenses to both platforms.
Activating the integration in Postal
Go into your account preferences and click integrations - Outreach
Click the Outreach logo and toggle it on
Select the boxes that match best for what you would like to sync from Outreach.
Activity from Postal will sync back to Outreach on the contact level
To start sending one-offs while working in Outreach, you will need to download the Postal Everywhere extension for sending Postals
Now it's time to create Triggers for Outreach. Please see the article Outreach Triggers for more information.