Picture (click) -- You don't "enable" quests, you just create the individual quests and it enables itself automatically.
You can also change the text on the actual thing that says "Quests (F9)" in the gmaeplay interface. People change it to things like "Info (F9)" or "Help Menu" if they want to include information about the map or help information.
Guys just a heads up I am going to be shutting the site down soon. I am just waiting on the NUON people to decide whether they want to transfer forum data and keep the discord. My email is [email protected] for anyone that wants to keep in touch and I have a facebook too. I will make an official post later. Love you guys and will miss everyone!