I’m sorry to hear you had troubles with Smart Slider 3.
Could you please tell me where did you get stuck? Which Editing mode were you using?
Canvas mode is indeed not so easy to adjust responsively, but this video should help:
If you would be using Content mode, which is the default editing mode, this mode was designed to be able to create a good responsive result fast, with minimum adjustments on mobile/tablet. I recommend the following videos to watch: