First and foremost design your view, preferably in something like Sketch or get an idea of what do you want as a scrollable content.
After this make the view controller free form (choose from attribute inspector) and set height and width as per the intrinsic content size of your view (to be chosen from the size inspector).
After this in the view controller put a scroll view and this is a logic, which I have found to be working almost all the times in iOS (it may require going through the documentation of that view class which one can obtain via command + click on that class or via googling)
If you are working with two or more views then first start with a view, which has been introduced earlier or is more primitive and then go to the view which has been introduced later or is more modern. So here since scroll view has been introduced first, start with the scroll view first and then go to the stack view. Here put scroll view constraints to zero in all direction vis-a-vis its super view. Put all your views inside this scroll view and then put them in stack view.
While working with stack view
First start with grounds up(bottoms up approach), ie., if you have labels, text fields and images in your view, then lay out these views first (inside the scroll view) and after that put them in the stack view.
After that tweak the property of stack view. If desired view is still not achieved, then use another stack view.
After making your view, put a constraint between the mother stack view and the scroll view, while constraint children stack view with the mother stack view. Hopefully by this time it should work fine or you may get a warning from Xcode giving suggestions, read what it says and implement those. Hopefully now you should have a working view as per your expectations:).