An indico account is mandatory for registration (required to issue a CERN access card).
In case you do not have an account yet, please follow these steps:
Open a CERN lightweight account visiting the following page:
https://account.cern.ch/account/Externals/RegisterAccount.aspx
Connect your new CERN account with the indico system by login at the indico page (https://indico.cern.ch).