Yes. Even if you are only attending as a spectator or alongside another attendee, you will need to purchase your own badge to attend the Galactic Championship event. You can find the different ticket tier options on the Ticket Information page. 

Entry to paid Organized Play events—including both the main tournament and side events—can be purchased separately on Melee.gg.

Tickets to participate in Organized Play events—including the main tournament and side events—will be sold on Melee.gg.

Make sure you are registered on Melee.gg and that your account is linked to your Star Wars: Unlimited Organized Play ID. Do so by logging into your My asmodee account through your Melee.gg account settings, under “Game-specific Info”.