iCloud Activation Locked

It can only be solved by the original owner. Only they can remove the activation lock. If you cannot do that, the phone is useless. Your only option is to return it to wherever you bought it for a refund.

There is no 'solution'.

There is no way to bypass the activation lock.

If whoever you got it from can't or won't remove the activation lock and you can't get a refund, turn it over to the police.