As something new, the e-conomic introduced a 'Grant Access Token' system. Through this token is given access to accounts API, where in the past would have handed Agreement No, User ID and Password.
IEX supports the new token system, and to get started with IEX integration you need to provide access via e-conomic.
You will see this page:
You must copy this token that looks like this string: c3FN7OUHXJXIJKLx0bomudB0e7SbgkGPk4YxUT + Uzt0 =
Send token to firstname.lastname@example.org with an indication of the customer you are.