There is an official free student licence
from Microsoft (for participating organisations)
Or there can be a student discount
For Office 365 it is by subscription (which can be paid monthly or as an annual one off)
Subscriptions always cover the current version of office
For a one off you can buy Office 2024, and keep it forever (or as long as it works on computers of the future)
For free you can just set up a Microsoft account for the online apps and some hosting space
Businesses sometimes have a licence that ‘entitles’ staff to buy a discounted copy (you register via a link with your work email address)
I used to do that, buying a discounted copy of the desktop software and combine that with the free online and phone apps
But now it’s subscription based the discount is not worth it on a personal licence so I have a standard subscription (it may be worth the
discount on a family basis depending on the number of users who need more than the free elements)
https://www.microsoft.com/en-gb/education/products/office
https://www.microsoft.com/en-gb/microsoft-365/college-student-pricing
https://www.microsoft.com/en-gb/microsoft-365/buy/microsoft-365
If a free or cheap option doesn’t work for their email address etc then OpenOffice should be compatible (or Google equivalents), and when required the free online versions can be used
But note that online apps don’t have identical capabilities to the full desktop versions
It will depend on their needs - eg compatibles and online versions would be sufficient for general documents, but if their is anything technical or advanced then they may find they have issues and/or if using different software their tutors may not be able to assist