I noticed in this blog post that it appears that a message field is able to span multiple vertical rows within the admin. Is this done by using a regular message field and then a group field for the items on the right? Is there another way to get fields to span multiple rows within the admin layout?
Here is the image showing the row layout:
I imagine that the image used on that page is from an older version of ACF. It was just caused by setting all of the fields to 50% width which would cause sorter fields to stack up against the taller field because they were all floating to the left.
To get this effect with the latest version of ACF would require adding your own classes, CSS and possibly some JS.