@randalhicks +1! If it helps, from a lot of posts I've seen on here and Reddit, Stadia support are saying it may take 3-5 business days and to contact them if you still haven't received the code by the end of the week…
Looks like you can return it within 15 calendar days after the day you received it...
@randalhicks Here's how you can get a refund:
From the FAQ
If I return my Stadia Controller or Chromecast Ultra, will my subscription be cancelled? Will I be refunded for the Founder's Edition?
If you return all of the contents of the Founder’s Edition within 15 calendar days after the day you received it, your 3-month Stadia Pro subscription will be cancelled and you'll be refunded for your purchase. Returning the Founder's Edition also means you'll lose access to the games you claimed as a Pro subscriber, your Founder's Stadia Name will revert to a standard Stadia Name, and your Founder's Badge will be removed. If the Buddy Pass included with your Founder's Edition has not been redeemed at the time of your return, the Buddy Pass and 3-month Stadia Pro subscription will be voided. If the Buddy Pass has been redeemed at the time of your return, the included three-month Stadia Pro subscription will be cancelled and the redeemer will lose their Stadia Pro benefits.
And here's more specific instruction. When I opened this, it automatically shows for US and Canada, but you might get something different. The idea should be the same though.
Get a refund on Stadia in US and Canada
If you haven't got the package, you can just reject the shipment when it arrives (it works in US, not sure where you're based) and you'll get full refund.