How to get "Meet and greet" Achivement?

[Kiara_Valentine]

Hi, I've found one guide for the Achivement "Meet and greet",
(You got your Project Silcharde poster signed by Mango Protocol!

Grab the poster that's on Nika's bedroom door. Go outside to the left of the streets until you get to a cafe with people outside. Speak to the girl and boy who are sitting together. Eventually you can get them to sign your poster.)
but when I interact with them I can't find any dialogue for the poster...
Please, help.