Quick Join was a part of addon LookingForGroup. However, natively supporting quick join proves to be an overhead for LFG and often not work properly. I decide to separate this sub feature into an individual AddOn which calls LFG apis to support this feature.
Why do you need this addon for joining Quick Join? The answer is very simple, you can filter people according to LookingForGroup addon filters. Filter spamming in Quick Join etc. Blizzard's default Quick Join is just annoying for most people and you always want to shut them down.
You must install AddOn LookingForGroup first.