I have received this advice from Support:
I would like to let you know that I have tried this on my end using one of our test devices and I was able to use the smart quote or the curly quotes. Please see the attached image in this reply for reference.
With that being said, below are the keyboard shortcuts I used to input the smart quotes in Evernote:
To produce an opening single smart quote, press simultaneously on Option + ]. To produce a single closing smart quote press on Option + Shift + ].
To produce an opening double smart quote, press simultaneously on Option + [. To produce a double closing smart quote press on Option + Shift + [.