There is no upgrade path from Windows 7 to Windows 8, and never has been. It must be installed from scratch, and you must acquire a license key for it.
The only free upgrade path was from Windows 7, 8, or 8.1 to Windows 10.
Personally, unless they're paying you, I'd refuse to install Windows 8.1 at this point. It makes absolutely no sense to do so.
Brian - Windows 10 Pro, 64-Bit, Version 1909, Build 18363
The purpose of education is not to validate ignorance but to overcome it.