I stacked with that problem as well. Found a good guide that helped me:
https://useyourloaf.com/blog/scroll-view-layouts-with-interface-builder/
Basically what you need is 9 constraints (assuming you want to scroll only vertically):
1-4: ScrollView to Superview (top, bottom, leading, trailing). Make sure to connect it to parent view and not to safe area.
5-8: Content view to Content Layout guide (top, bottom, leading, trailing)
9: Content view Width equals width to Frame Layout Guide.