Thank you for posting! So sorry you were running into that error when trying to add your Facebook link. When you were adding the link, how were you inserting it? Did you create a clickable link to your Facebook account or were you using one of our Social Media buttons?
If you were creating a clickable link, were you copying and pasting the URL directly into the block? If so, I would try following these directions on how to add a link to your campaign.
Otherwise if these were not the steps you followed, could you explain what steps you were taking when creating this link?