Timeline Training Wheels

Unable to get the timeline training wheels to work

Hi there!
I read about the calendar overlay and wanted to try it. opened chrome, opened workflowy, found the link in the workflowy email and set up the extension.
but nothing is happening. click on the extension name: Nothing. all else seems to be in order. do you have a FAQ somewhere that might have some suggestions for me? I tried installing a different chrome extension and that went well so I don't seem to be doing anything wrong immediately.
hope you can help!
Eva