This is actually a serious problem because it appears that you may have more than one Apple account connected to this device. And the one you can't remember the password for is the one your FindMy is linked to. Not only is this preventing you from resetting the Mac, but if someone else were to access the Mac through FindMy, they can actually remotely wipe the computer, so it's a security vulnerability.
Apple provides guidance for recovering a forgotten Apple Account password:
If you forgot your password and can’t sign in to your Apple Account - Apple Support
Whether this will work or not may depend on whether you have access to other trusted devices (such as an iPhone) for that Apple Account. But I suggest you follow all the options presented in that link, carefully.
Your NSURLErrorDomain error is typically from a failed network request. This might be related to your Apple Account situation, but that isn't clear. The 1012 error code can be from an authentication, password, or security certificate problem.
This could be complicated and time-consuming to troubleshoot remotely in a forum discussions format. I suggest you not try to download any more OS updates, but rather follow all options in the above link to resolve the Apple Account problem. If none of them leads to resolution, I would contact Apple Service Apple Repair and Repair Status Check - Official Apple Support or maybe better yet make an appointment to take your Mac in person to a Genius Bar because I expect you will need some special assistance to resolve the Apple Account issue from Apple unless you achieve success with the first link I provided above.
User level: Level 1 (4 points)
