Were to get a robot class in aqw

If you are talking about rustbucket, enforcer, and partosartorium.....

rustbucket-finish mithril man battery quest in crash site
enforcer-class drop from mithril man in crash site
partosartoium-class drop from the partosartorium in crash site (member-class)


no, rust bucket comes from the protosartorium parts quest