As well as registering as a CERN User, in order to access the CERN site, you will need to take the following two extra steps:

• Take the Covid-19 online course found via
  https://lms.cern.ch/ekp/servlet/ekp?CID=EKP000043435&TX=FORMAT1&BACKTOC…
• Complete and sign the CERN Covid-19 declaration found via https://edms.cern.ch/ui/file/2371462/LAST_RELEASED/Declaration_of_Honour-COVID-19-2-ENGLISHbis_docx_cpdf.pdf

For more information about Covid-19 measures at CERN see https://cds.cern.ch/record/2718608/files/COVID-19_QuickRefGuide.pdf