The link you followed will bring you to this page:

https://www.autobus.it/unico-na/login/it/auth/sso-login?returnUrl=https:%2F%2Fwww.autobus.it%2FIdServer%2Fconnect%2Fauthorize%2Fcallback%3Fscope%3Dopenid%20email%20profile%26response_type%3Dcode%26client_id%3Dtplweb-unico%26redirect_uri%3Dhttps%253A%252F%252Fwww.autobus.it%252Funico-na%252FTPLWebPortal%252Fit%252Fauth%252Flogin-callback%26state%3DQmRvWkFFN1NJYWc1aGN4ajdPbENWVWJsRXRGaHhsSFg%253D%26ui_locales%3Dit%26code_challenge_method%3DS256%26code_challenge%3DU8uNdOeLMtU8QW4qfWtOTtiE2LXu0bCWtFpIE1SgJKY