CERN is changing the authentication interface - some applications still use the old one (as shown in your screenshot) while some applications use the new one. If changes are made in the new interface (e.g. password change), then this is not necessarily propagated to the old interface.
Please note that the CERN FLUKA user forum uses the new interface, while the FLUKA website fluka.cern still uses the old one. However, download of the FLUKA packages on fluka.cern (Download latest FLUKA release | The official CERN FLUKA website) is based on the new interface since the packages are hosted on another server. So it is not necessary to login to the old interface on fluka.cern, since you will be anyway forwarded to the new interface.
In case of problems with the new interface, please also see: