Cannot install PC Drivers

So, I'm trying to install TWRP on my Idol 3. I followed all the directions I've found. Basically I get to the point where I change the connection to the PC to the CD drive so that I can install the drivers. I go to install the drivers, and it fails every time. I've tried it on 3 different Windows PCs. I do have a mac at my disposal, would this be easier? I'm seriously going crazy trying to figure out why I can't root this phone! Any help would be appreciated.
Thanks!

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