I was using an older (paid) version of Outlook 2016, and today received an email from Microsoft saying that 'Outlook is now free for all Mac users'. The 2016 version has always had a few issues and lacks some features, so I jumped at the opportunity. I clicked the link provided in the email, which took me to the Apple Appstore and installed the new version.
However the updated version won't go online as it says I need a 365 subscription! After spending all morning investigating and trying to fix this, I gave up. Luckily I had a backup of the older app which I restored.
I finally found this support article now. I refuse to waste more time digging around on the Microsoft website for the correct, working (free) version - just to end up rolling back again when further issues arise.
This is complete rubbish from Microsoft. Why send out an email which ends up installing a non-working version from the Appstore??!