That is the correct link. Easiest way is to use hansoon's tool. Follow the steps to unlock bootloader, root file and recovery are included in the tool. Just make sure to research what you are doing BEFORE you start, and read ALL directions. Happy flashing!
Sent from my HTC One_M8 using XDA Premium 4 mobile app
AT&T HTC One (M8) - unlocked/s-off/rooted stock
Asus Transformer TF701T - unlocked/rooted stock