Ok, check this out. I got them working with the most up-to-date versions of each, but I had to reinstall them both directly from the downloads, not use the update path. Furthermore, I had to install Pro first, then the calendar or it wouldn’t work. Tried numerous times and this was the only way it worked for any version combination. Pro first then calendar.
Don’t know why.
Doesn’t matter really; working now so I’m happy.