So you linked to a random answers article (not a good sign) which in fact isn't even about the product being discussed (it's Word, not Outlook). In addition the ad they mentioned isn't an ad at all, it's a resume assistant feature offered as part of the linked in service and doesn't show up unless you open that feature.
I use office 365 and I've never seen an ad (and I would drop microsoft immediately if I did, they are on a very short leash already, although they don't show 3rd party ads their software bags and annoys the f* out of you and makes every effort to steal you data, even on a business subscription, but I digress)
The linked thread talks about a "home" version, and I have (I assume) a business version, though I dont remember seeing an option, that may be why
I just checked my copy of Word, and honestly that doesn't feel like an ad. Seems like a pretty cool feature for a lot of people, and your link shows how you can disable it through settings.
It's not asking for money nor does it save your personal information, it's just a Github CoPilot for resumes.