The participation at the Workshop is by invitation only. A number of seats have been reserved for local participants - members of the Heidelberg Graduate School of Fundamental Physics.
Even though there is no registration fee, both the invited speakers and local participants are asked to register at the CERN Indico page of the Symposium. Here is the list of registered participants.
The organisers provide accomodation and cover travel expences to the invited speakers. See this page for further details of travel cost reimbursement.