Hi! So I'm new to the game (I know! A bit late to the party) and my nephew also plays. He likes it when I make levels for him on games that allow it so I've started making a Fortnite level for him on creative mode. I've got an island, plonked down like 6 different buildings, now what I want to do is something with keys or key cards that he has to find and collect in each of the 6 buildings (which will be guarded by sentinels or the other guard thing which I can't remember now). Then only when he has all 6 keys can he open the final building or portal or whatever. How would I go about doing this? Is it possible?

Would really appreciate the help.