Now you link a real account, identified by an email address. This is a two-step, signed exchange.
POST /email-verification-messages
Body:
{ "email": "merchant@example.com" }
This emails a short code to the merchant. Success is 204 No Content.
PUT /woocommerce/adyen/backoffice-user
Body:
{ "email": "merchant@example.com", "code": "123456" }
The code is what arrived by email. Please note, that code's lifetime is only 1 minute! On success (204), the account is connected. From here, the account-level actions (contractors, stores) become available.