After grabbing the USB stick for Officer Pike and leaving your apartment, you'll automatically be transferred to the festival site. There will be an automatic cutscene with Ryan and Steph. Once you get control of Alex, turn around and walk towards the stage. The "Drum Kit" that you'll need to interact with will be on the left side of the stage. Hold "LT" and then the "A" button, listen to the memory play out and the achievement will pop!