well it kind of help the link but anyway you just need to do the last part of this video kill mini boss then push the button at the end of quest this video show it in jungle but you need to unlock it in mountain and seaside to
you can do it on normal-ultimate mode but whatever one u do is the one it be unlock for like if you do it on vh mode then it be unlock for vh mode only to u unlock it for the others
and im busy now with stuff so gl found some help should be easy just make a room name Unlock CCA and hopeful a high level player will come to help you