Auto play is for continuous playback of a playlist from one track to another
you are looking for auto cue like the CDJ's have pretty much where when you load a track it is paused and cued at the first sound and ready to play, that feature is not in rekordbox DJ, similar to the way Serato works, if you have a track playing and you load a new track it will continue in play mode, if you stop a track, then load a new one the track will still be stopped until you hit play