Fully complete a run of Super7Just to the south-east of the Horizon mainstage, near the Sierra Nevada Dam and to the west of the Cordillera area, you'll find a "Super7" icon. This is where you'll want to head for this achievement.
The Super7 is basically seven community made challenge events that you need to pass, one after another (although your progress is saved so you don't need to do them in one session). These events aren't set, so if there's one you're struggling with, just reshuffle the card, basically. But yeah, super straightforward: just do all seven events and this achievement is yours.