Similar deal to this one but you get US$10 credit instead. I've just signed up and waiting for credit now.
Enjoy two free months of Audible. You’ll receive one free audiobook of your choice each month, and an additional free NSLS-selected audiobook each quarter. After you download your free trial you will receive your $10 Amazon Credit to your Amazon.com account. Amazon Credit offer only valid for existing Amazon customers.
Membership can be cancelled at any time but make sure you get your credit first!
T&Cs
Offer is available until June 31, 2019 at 11:59 PT or while supplies list. Valid for U.S. Customers Only. Offer is not available to existing Audible members. Offer good for a 2 month Audible free trial, a $10 Amazon.com promotional credit, and a free audiobook every 90 days chosen by Audible and the National Society of Leadership. To receive the free quarterly audiobooks each 90 days you must have redeemed the Audible free trial via this offer and remain an Audible member or trialist at the time the free quarterly audiobook is distributed. You will receive a two-month Audible free trial that includes 2 credits as part of the standard Audible Monthly Gold Membership plan. At the end of the free trial, your membership will continue until cancelled at the then current full price (currently $14.95/mo.) with your designated credit card or another available card on file. Cancel anytime by visiting the Account Details page. After you successfully sign up for the Audible Trial, and your account is verified as described above, within 2 weeks you will receive an email notifying you that the $10 electronic Amazon.com promotional credit has been added to your Amazon account. The Amazon.com promotional credit only applies to products sold by Amazon.com (look for “sold by Amazon.com” on the product detail page.). The Amazon.com promotional credit may not be used on digital products. Products sold by third-party sellers or other Amazon entities will not qualify for purchase by the Amazon Credit, even if “fulfilled by Amazon.com” or “Prime Eligible”. Shipping charges and taxes may apply to the full value of discounted items in your order. If any of the products related to this offer are returned, your refund will equal the amount you paid for the product, subject to applicable refund policies. Offer is limited to one per customer and account and may not be combined with other offers. This offer is non-transferable and may not be resold. Audible and Amazon reserve the right to modify or cancel the offer at any time. If you violate any of these terms, this offer will be invalid.
Credit to Slickdeals
Thanks to doweyy for title.
From previous deal: "The terms and conditions state that you must be a U.S customer, however if you press "Go to Audible.com" you are able to complete the offer".
Worked for me.