O365 admin portal reporting

Well, the Office Activations report seems to show whether a user has downloaded and activated Office desktop click-to-run, but it doesn't show the version number in use (could be important if you want to check lingering updates required for new functionality), nor does it show anything about MSI versions of Office (as far as I can tell) or whether old versions of Office (before 2016) are used. I also don't trust the dates because I can see an entry (in my tenant) for a user who apparently activated Office 2016 for Mac on 10 Nov 2014. It probably is that this is the date that Office for Mac was first activated on the machine and the date wasn't changed when subsequent updates were applied... I also see three activations for Office on Windows Phone for my account (but I have one phone) and 1 for iOS (I've activated on at least one iPhone and an iPad).  In short, some of the data is a mystery... and because you can't drill down into the data to check what lies beneath, it will remain a mystery.

I don't believe that any of the third-party reporting products do any better. This is because they all depend on data provided by Microsoft through a reporting API... and that's what Microsoft is reporting here too.