Overall the experience makes me think that it’s going to ultimately be a windows 11 issue (this is apparently the ultimate requirement for the accounting package) - unless the way another OEM configures manages to avoid the Microsoft account, advert pushing and O365 direct to New Outlook?
(As a side note, I’ve previously had them using parallels on a Mac. It worked but it was hard work. My parents are both brushing 70. They’re familiar with Outlook - when buttons change it blows their mind. I’m sure everyone in here has had to deal with parental tech support - now try managing it when you’re 900km away and they’re using an operating system you’re not even familiar with any more)