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Go to your Confluence settings by clicking on the Cog Icon on the header bar.
In the sidebar, under Salesforce, click on Connections.
On the Connections screen, click Add Connection.
The Add New Connection pop-up window will appear.
Enter a suitable name for your Connection then click Create.After the new Connection is added, you will still have to Authorize it.
Choose the type of the Salesforce instance, then follow the authentication approval screens.
You're now good to go!