I was able to install on both iPhone and iPad, but the nonexistent installation instructions (at least I could not find any) caused a bit of floundering. Then, once installed, the app would not run because the certificate was not trusted. Some Googling revealed that what I needed to do was select the Evernote Corporation profile under Settings > Device Management and "Trust" it.
Can you folks describe what "doesn't work"? What steps do you follow and what goes wrong? It's a complicated setup requiring that you install a profile, and you have to click on the link Evernote gave you from Safari and not any other browser.