My mom had to buy a copy of MS Office. Her university provided free ms office online, but there were certain features missing from it she needed for her papers. I am remembering wrong, but it was annotations? Citations? I do not remember.
Libreoffice kinda could do it, but I could not find how online, while MS had it properly documented on their website and so many youtubers making videos on MS Office had it listed on their website.
Edit: also found out MS Office can screen record and record her webcam. Very useful for her giving a remote presentation during covid.