Just received below email from Amazon :
As a new member to Audible, we want to help you get the most out of your membership. Expand your options to listen to your favourite audiobooks around the house. Eligible members who complete this below step will receive a free Echo Dot! (10,000 units available)
Just listen to any audiobook for an hour. It's that easy!
✔ Once you have completed listening, we will confirm your eligibility and send you an email for next steps.
✔ Look out for an email from Audible within 7 business days to find out how to redeem your free Echo Dot.
Are you a paid member of Audible or doing a Free Trial?