The feature supports Case objects only at the moment. Based on the following documentation:
Hi everyone, we have rolled out the improvement request on this idea. You can now associate a Salesforce Account, Contact, or Opportunity with a Confluence page. This is mentioned in this documentation.
Thank you for all the votes given on this idea. You should be able to see this improvement already in place, in your Confluence. If you have any issues, please reach out to our 24/5 support team at https://servicerocket-apps.atlassian.net/servicedesk/.
If you have any other requirements for any other Salesforce objects that are not mentioned here, please let us know by commenting on this ticket.