Slider strip

Dumb question but how does one get started using the built in slider? I am using plugins on ableton. Doesnt seem to recognise it through midi. Does it get used to play notes or control the mod wheel?
Thanks in advance

Please help!!! I have looked though the manuals a few times and would really love to know how to use this feature

Make sure you’re in diatonic strum mode and you can use it to play the notes of the chord.

But it would be cool if it could be mapped to other things in ableton