Following the announcement , a highlight medley of the group 's debut mini-album was released on June 24 .
Group eventually debuted , on June 28 , 2016 , with the mini-album , Act .
Following the announcement , a highlight medley of the group 's debut mini-album was released on June 24 and they eventually debuted , on June 28 , 2016 , with the mini-album , Act .