Advents are 100% Solo Events. You also need to be able to beat Ultimate if you want to get the SSR Eido and the Weapon. 275 Gold Mats are required for that and Ultimate ( 40 AP per Run) can give you 4 Gold Mats, while Expert at most can give you 2 Gold Mats ( 30 AP). Collecting SSR Stuff in Advents gonna be easier in the Future but right now, Advents are the worst Event in this Game for a Newbie.