There's no stupid question (in my book). We've all been newbies on this stuff at one time. Actually, I think intelligent folks are the ones that ask questions or seek advise.
Look's like my suggestion about "automatic" is in fact what's happened.....and you made 25 cents on the "deal". I've seen similar EMails.
Auctiva's Insurance Plan is with a provider named UPIC. They actually have their own website and are an established shipping insurance provider. http://www.u-pic.com/ You don't really need to deal with them, just Auctiva for purchase under their plan.
Long-story-short, when you buy insurance from Auctiva, you get it at a discount and the actual provider is UPIC. Your buyer pays the typical USPS rate (like $1.65 for a $49 item including ship) and you pay Auctiva $1.40, making 25 cents for the deal. The plan covers 100% of the ebay transaction including the shipping. That's actually better than USPS insurance (or other carriers), which only covers the item's final value.
When I buy Insurance for one of my sales, I also click off sending a copy of the policy/coverage to my BUYER. That's something that's done on that Transaction page I mentioned. Do the VIEW INSURANCE. That way the Buyer knows they are COVERED, as no insurance info is on the actual package (like the USPS sticker for theirs). I'd also check your account to see if you now owe Auctiva $ for that purchase (guessing $1.40 since you made 25 cents). You now get billed monthly, but can deposit money and/or pay from PayPal.
If you haven't looked at all the details on the Insurance Plan including how to file a claim, it's just about all there in the FAQ section from HELP link (top of any Auctiva page).
See....told you not to panic. Looks like it's all done but the shipping.
Danno