I really was only commenting on your (very real) concerns for other readers of this thread in the future.
If someone else is also concerned about using a network public site (the two mentioned in the directions are in Canada and China) that they do not control the content of . . . .
OR
If setting up an 'in house' network is too challenging. . . .
There is another way - requiring only the contents of the zip archive and the Kindle to be jailbroken, see:
https://www.mobileread.com/forums/sho...73#post3265373
(Another one of our regular contributors - with even less free time.)
Note: I made a couple of errors in my post - I'll fix that now.