Louis is concerned that John Deere has taken the attitude that farmers don't really own the tractors they buy, and as such, they refuse to provide support to repair the software that drives the tractor. Because computer code snakes through the DNA of modern tractors, farmers receive “an implied license for the life of the vehicle to operate the vehicle” but do not own it.
Windows, or any operating system with multiple users, assigns ownership to every file. This means if you're not the owner, you can't modify that that file. The administrator account is able to access all files on the system, but Leo doesn't recommend running as administrator for security reasons. Running as a "limited" or "standard" user will significantly decrease the chance of having malware installed on your system without your knowledge.
Ken had a hard drive go bad on him. He replaced his computer and got a docking station so he could access files on the bad hard drive. But it won't give him access without permissions.
Leo says that Ken needs to "take ownership" of the old files. PadreSJ says that Microsoft has a tech note on how to take ownership of a file or folder.