With all your branding changes over the years, what's considered a Microsoft account today? My old Hotmail account, that existed from the days before Microsoft bought Hotmail? I think it's still alive, but I haven't logged in in the better part of a decade to find out. The accounts created over the years for various Xbox machines? I think those are still around, but I doubt I could get into them at this point. The "Live" account I had to create for MSDN many years ago? Once that job and associated need for MSDN ended I've not logged in to see if it's still around.
Which one(s) should I try to find login information for to use?
Furthermore, why must I sign in in the first place for the free version? I can understand signing in to associate the install with a paid version with extra features, but I see no reason to require it for free versions without any paid features.