You can download it for FREE from here, and up until 6/20/22 on the Google Play Store.
If you insist on using the Google Play Store, you can request a promo code by signing up here:
insert form here
My policy is that I don't have a policy. I don't collect anything from you. You can play the main game entirely offline.
The Sandbox level sharing feature will be online after the initial release. This may collect a username and a password, but that's probably it.