Appearance of a fixed block when scrolling?

Question

css

There are several sections:

<section>
 <div>popup</div>
 <div>content</div>
</section>

It is necessary that a div with a pop-up appear when the section scroll is reached, I tried to do it through wowjs and give absolute positioning, but when the pop-up appears, it is necessary that it would not be possible to scroll further, that is, the pop-up must be fixed, it is no longer possible through wowjs, since the popup appears already when the page is loaded
Help plz)

Answer 1

Try nivoslider or owl.

Answer 2

See how affix works in bootstrap