The Caminito is one of the few things around here you genuinely cannot leave to the last minute. There is a hard daily cap, nothing is sold at the entrance, and in spring and summer the slots go weeks ahead. If you arrive without a booking you are turned away at the first checkpoint.
The official self-guided ticket is the cheapest, but it opens for a season in blocks and a big chunk sells within the first day, so an empty calendar usually means that batch is simply gone rather than not yet released. Keep checking, because cancellations do reappear, especially for midweek mornings.
If the official self-guided slots are gone for your dates, a guided tour – either the official guided ticket or a tour operator that bundles transport from Málaga – is the normal fallback. It costs more but it is a real walk with a real guide, not a workaround. Our
Caminito del Rey guide explains the options and the timing. Which week in May are you aiming for?