1. Open Planner from Office.com:

2. Open up the Plan you want to Sync to Outlook Calendar:

3. Click on the 3 dots next to the Schedule Button up the top:

4. Click on Add Plan to Outlook Calendar. You will need to select Publish. Then click Add to Outlook:
5. This will open up Outlook Webmail with a sidebar on the Left side, Click Save:

7. It will take a few moments to sync to the Outlook Client App on your computer, Once it has, Open up the Calendar Section in Outlook:

After this step, Anything inside the planner with any tasked assigned to your name should sync across.

Hope this Helps.