ALC stands for Adventure Lab Cache and it’s a new type of cache. There is a special app for this called Adventure Lab. This mystery cache is a bonus cache for the lab cache "河樂廣場 / Hele Plaza".
First of all, download the app and click the link below. Visit 5 locations and complete the tasks. The bonus code will provide in the journals which can unlock the bonus cache.
https://adventurelab.page.link/VU3k
You can validate your puzzle solution with certitude.