It's highly unlikely that you actually need
any version of Microsoft Word at all. Most AB members (including me) use one of the free alternatives, with Apache OpenOffice being by far the best-known:
https://www.openoffice.org/
(It's what I use)
LibreOffice also has plenty of fans here:
https://www.libreoffice.org/
WPS Office Free is less well-known but also gets excellent reviews in the technical press:
https://www.wps.com/office-free
(If you need an email client to go with one of those offerings, instead of Outlook, Thunderbird is excellent:
https://www.thunderbird.net/en-GB/ )
If you really want Microsoft Office (WHY?) then, rather than looking for 'Office 365' (where the "365" relates to how many days you get for your money, meaning that you have to keep renewing your subscription), you need to seek out a version of Microsoft Office which has the year of its release in its title. The latest version is Microsoft Office 2016
https://www.microsoft.com/en-gb/p/office-home-student-2016-for-pc/cfq7ttc0k5fc
(Note that you don't get Outlook in the 'Home & Student' edition. You could either switch to Thunderbird or, if your budget allows for it, buy the 'Home & Business' version:
https://www.microsoft.com/en-gb/p/office-home-business-2016-for-pc/cfq7ttc0k5ff )
You can also find older versions of Microsoft Office (such as '2013' or '2010') offered online at cheaper prices.
However, as I've suggested above, a free office suite (backed up by Thunderbird as your email client) will probably meet all your needs anyway.