Add friends at Fortnite?

Have seen one that is not on Fortnite in my platform, but unfortunately the name and not epic or email name, how can I add it trz?

If you were a teammate (or nice opponent) and you want to be friends you have to add in the game because your teammate is listed and also available for selection "add to friends" (or something like that)

if you did not remember the name and did not invite him in the game, you lost the guy