Animation based on scroll with fixed widget group doesn't work

I wanted to make this oppacity animation based on scroll. I learn it with this tutorial on the Readymag’s offical youtube channel. https://youtu.be/wQO12RjDg-o?si=KEqsZkiIMPrMNarv

But it doesn’t work with widget group. If I fix on screen my widget group, I can’t decide when it will desappear. What ever I do with offset options, the oppacity animation starts when I start scrolling.

Does exist a new way to do it ?