In reply to dereke12000:
It seems you have to register in advance...
Some information copied from this site:
http://www.caminodelrey.es/
The pathway will allow 50 people at half hour intervals from each access point (El Chorro and Gaitanejo)and the maximum number of people allowed to be on the path at any one time is 400 The path is
closed on Mondays plus December 24th, 25th and 31st, and January 1st.
Entrance tickets to the path El Caminito del Rey will be free for the first six months after the official opening.
Climbers who want to access climbing route will have FREE access to the Caminito del Rey but must show their public liability insurance before being allowed to enter. Climbing can only be practised BELOW the Camino del Rey in order to avoid rockfalls on other visitors