I think the option is found here:
- With the Text Box selected, choose Format>Shape from the OS X menu at the top of your screen. The Format Shape pane opens.
- On the Shape Option tab, click the blue square with arrows (it's called Layout & Properties if you hover your mouse over it).
- Click on Text Box to expand the options.
- Check Wrap text in shape at the bottom. OK out.
However, even with that checked, I can't get text in a text box to wrap around another text box or frame in either Word 2011 (the version used in the previous thread) or 2016, which is what you're using. I have no idea how Daniel Grau got that effect in the previous post.