Hi berloth,
I can help you out with this.
Due to Facebook API limitations we are unable to import events directly from profiles using their username. That is only possible through Organization or Page usernames.
You can import events from profiles using the direct id of the event. That is found in the event link.
I would recommend watching our new user primer as it explains what events can be imported and gives examples on how to find the id.
https://theeventscalendar.com/support/documentation/facebook-importer-new-user-primer/
Let me know if you would like some more help after reviewing that guide.
Thanks