Billing-portal links are temporary. Reusing an old tab, bookmark, or shared link can fail after it expires. Billing actions also require the right team and an authorized account role.
Open Billing in the Console and request a fresh portal session for the intended team. Use the relevant purchase entry when looking for a payment document. If the new session still fails or a confirmed purchase has no expected document, report its reference and the visible error. Do not forward a private portal link to support or another person.