From the top-right corner of the page toggle Edit mode into the On position.
Locate the Add a Block item at the top of the expanded Block drawer on the right side of the page.
From the Add… menu select Course Completion Status.
From the Secondary navigation open the More menu.
Select the Course completion item.
There are the Suggested settings, although you are free to experiment and play with other settings.
Scroll to the bottom and click the Save changes button.
Return to your course. The Course Completion Status block should appear as the Configured version (shown below) if your setup is functional.