That’s funny. My husband’s PC keeps freezing, giving a “disk space full” message, and supposedly the upgrade is to install Windows 10, only it won’t install - the download halts about 20% done, every time.
Might be time to upgrade that 40 MB hard drive you have had since 1988......................
I’m guessing he has a newer computer with a solid state drive for the operating system?
Those drives are pretty small, usually just enough to hold one operating system, documents, and temporary files. If you try to download the upgrade to that drive there won’t be enough room, because you haven’t uninstalled the old OS yet.
I would try downloading the upgrade to another drive (not the C: drive, that is usually the smaller solid state drive). You can install the new OS to the C: drive, just don’t save the installation files there.