「関連付けられているアカウントはないようです」と表示される。

Hi touma.114070​ 🙂

You screeshot shows that it asks you for an email address given by an organization. That's not how it should be.

Perhaps you have selected business account instead of personal use whem setting up the Quest?

You have to factory reset the headset and set it up again.

How to factory reset your Meta Quest

If, even after the factory reset, it's still locked to business mode and you are not able to select for "personal use", bring it back to where you bought it and get a new one(that's not so easy in Japan as in my country, I think🙁) or contact support.

You can do that via email, chat or WhatsApp HERE