How do I become friendss with players after a hunt?

How do I add players as friends after a group hunt?
Is there a way to add players as friends after completing a group hunt, like a Hunt-a-thon or Dimensional Link?
Sometimes I play with random players and would like to add them afterward, but I can’t find any option to do so. Is this possible?
I’ve played with random players before, and somehow they were able to add me as a friend after the hunt. When I tried to do the same, I couldn’t figure out how to add them. Does anyone know how it works?