Why was I charged by Audible?

[Cookie]

Lots of youtubers have been promoting the site Audible and saying that you will get the first book free when you sign up so I did sign up a bit ago and got the book Looking for Alaska. About two days ago I looked, and they charged me 14.95 dollars and I didn't even but another book! Does anyone know why they charged me and is there anything I could do to get that money back?

[Siimonii]

I found this on their website:

Audible Free Trial Details
Get an audiobook of your choice, free, with a 30-day trial. After the trial, your paid membership will begin at $14.95 per month. With your membership, you will receive one credit every month, good for any audiobook on Audible.

Cancel anytime, effective the next monthly billing cycle. Cancel before your trial ends and you will not be charged. Check out the full terms and policies that apply to Audible membership.