When does Activation Lock turn on?
Activation Lock is enabled when Find My is turned on for a supported device. The account association remains relevant through erase and recovery, so wiping the device does not by itself release it from its owner.
What happens during setup?
When the device is activated or recovered, it checks Activation Lock status with Apple. If it remains linked, setup requests the Apple Account credentials associated with Find My. This ownership check is different from a device passcode, carrier restriction, or Apple Account password reset.
Legitimate ways to proceed
If you are the owner, enter the account details requested or recover your account. If the device belongs to someone else, ask that owner to remove it from their account. For a device you own with valid proof of purchase, Apple offers an Activation Lock support request. Outcomes are determined by Apple.
Before a second-hand purchase
Do not take ownership until the seller has erased the device and you can begin setup without seeing a previous owner’s account. Apple recommends checking this before buying a used iPhone or iPad.