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The app itself does not store any of your Confluence page content, it only stores page ids to identify pages to be synced.
How to use
Step 1: Configure.
Click on the "configure" button at the Zendesk Knowledge Sync section of the "Manage Add-Ons" page.
This will open a configuration form to set Zendesk API credentials.
Step 2: Activate page sync.
After you configured your Zendesk API credentials you can go to any confluence page and click on the button on the top right of your page to open a page options dialog. This dialog will let you select a destination to sync this Confluence page to. Select one and click "synchronize this page".
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