This means your iPad is under activation lock. Did you purchase it directly from Amazon or from a seller on Amazon? If the seller was Amazon, ask for a refund.
Activation lock can only be removed with the original proof of purchase from an authorized Apple reseller or from Apple directly.
Without the original proof of purchase Apple will not remove an activation lock.
Reach back out to the seller and ask them to remove the activation lock by going to iCloud.com and logging in with their Apple ID and password that is logged on to on those devices, then click on "all devices" and remove them from there. That will remove the activation lock. Or ask for your money back.
Activation Lock for iPhone, iPad, and iPod touch - Apple Support
How to remove Activation Lock - Apple Support