It’s still experimental , and it’s also very likely to be included in Discourse by default soon.
For now you could install the theme component from @Johani’s 
repo here: GitHub - hnb-ku/Discourse-mobile-user-cards · GitHub
It’s still experimental , and it’s also very likely to be included in Discourse by default soon.
For now you could install the theme component from @Johani’s repo here: GitHub - hnb-ku/Discourse-mobile-user-cards · GitHub