If you are still getting the error, please go to Events > Settings > APIs and under Facebook click the “Refresh your connection to Facebook” button. See here > https://cloudup.com/cLnBV-RjTW9
After this, are you able to import from that source? Let us know about it.
Thank you Victor, the refreshing Facebook solution worked.
Additional question for the future. When placing a FB URL the example in the field shows a URL for a page and the URL you suggested was the URL for the EVENTS of the Page. Will it work both ways? Or should I be using the URL for the EVENTS page of the page?