Couldn't find related post so sharing it.
You will see this message under eligible product listing
"Get 90 days FREE of Amazon Music Unlimited
with the purchase of any eligible product. Shop now"
Terms and Conditions
The offer is valid for the customers who bought an eligible product shipped and sold by Amazon AU on www.amazon.com.au. This offer is while stocks last. After the purchase of an eligible product, you will receive an email with further information on how to sign-up for a 90-day promotional subscription for an Amazon Music Unlimited Individual Plan. After the 90-day period, your subscription will auto-renew and you will pay the full monthly price of $11.99 with the option to cancel anytime. To receive the benefit of 90 days free of Amazon Music Unlimited, you need to sign-up within 30 days from when you purchased an eligible product. Excluded from the offer are customers who are currently in a free trial of Amazon Music Unlimited, are a current paying customer of Amazon Music Unlimited, or were previously a free trial or paying customer of Amazon Music Unlimited. Each customer can only participate one time in the promotion. This offer cannot be combined with any other offer. Only customers over 18 years can participate. The offer is not transferable and may not be resold. A cash payment is not possible. The offer is only valid for digital content and services offered by Amazon Australia Services Inc. Digital content and services may be local and restricted to customers in the Australia & New Zealand. Amazon reserves the right to cancel this offer at any time.
Any idea what "office supplies" are eligible?