Error:

Unable to list item. Before you can list this item we need some additional information to create a seller's account.

Resolution:

Is this a new eBay account?

If yes, then you'll need to fill out some security related questions on eBay first.

At the moment, the only way to list this item is directly from eBay.

When you do this, you'll get a series of questions that you must answer. This essentially validates and approves your eBay seller's account.