restore back up asking for itunes backup password any idea what this is? tried all nothing works

im trying to restore my backup from a pc for my new iphone 11. Im getting a message to enter a password to unlock the backup. I'm assuming its my apple password, but it does not work. I've tried it numerous times. Ive signed in with it and I just signed in to this community with it. Am I missing something? I even tried my phone password. ????Help!