To use OverscrollConfig, you'll want to make sure of a few things:
- ScrollRect's movement type is set to 'clamped' (OverscrollConfig disables itself otherwise, to avoid conflicting overscroll effects)
- The content is larger than the scrollrect (otherwise it wouldn't scroll, and thus wouldn't need to have overscroll effects).
- If you're changing the size of the content at runtime (even on Awake/Start), it's best to call Setup() on the overscroll afterwards, to make it re-check whether there should be overscroll effects and set itself up accordingly.
Apologies for the late reply, and while I agree the documentation is lacking, I can unfortunately only do so much with my time. Once I have things in a more stable state where everything is less sporadically changing, writing more documentation will be a higher priority - in the meantime, feel free to post questions here or email us, and we'll be happy to help :)