Before walking away, I’d first talk to management or HR. You can get accommodation for ADHD, and that might really be a game changer. Perhaps you can get an assistant to help with paperwork? Or you and your supervisor can work together to develop a system that works for you?
If that doesn’t work, it might be time to walk away or see if you can go back to your old position or a better suited position. I’ve been where you are. I worked as a bank teller and it was HELL. For months, I struggled to make it work, but my anxiety began to worsen and it got to the point that I would lie in bed at night not wanting to fall asleep because that meant morning, and therefore work, would arrive faster. It was no way to live. Everyone suffered. Coworkers suffered. Customers suffered. And I suffered. Walking away from that job was the best decision I ever made.
I read an article once that teaching is good for ADHD. Being a teacher means you could get promoted to principle, but the role of principle was a more administrative position. Therefore, while society tells us promotions are good, sometimes staying put is better for ourselves and our work.
I hope you figure things out.