A recent challenge has been simply getting this to work at all on Outlook 2016 for Mac. There are a few constraints:
In the end, I downgraded to version 16.12 of Outlook 2016 for Mac, as versions 16.15 and 16.16 both seemed to be somewhat flaky. Sometimes the button would appear after a few hours, but often not even then. As soon as I switched back to version 16.12, the whole process became instant.
Microsoft support did confirm there was an issue in recent builds, but didn’t know precisely when the fix would hit the public release stream.