If you haven't already you can find out how to integrate with Greenhouse here
Once done you can move on to selecting the roles you would like to link with Greenhouse.
1. Go to the "Integrations" tab at the top of your screen and Click on "Jobs not connected"
2. Choose the roles from Jobbatical you want to link and the corresponding role in Greenhouse. To choose from already expired job openings click "Show expired openings" to expand the list
3. Hit "save" to review your selection on the next page and then "confirm" and you're all done.
Please note it may take up to 15 minutes for the applications to initially start appearing in Greenhouse.