New (Oldie) Warmane player could really use some help

Hey everyone! So I started playing WoW at end of legit BC, played through till MoP. Some friends and I heard about Warmane and want to play some ole' WoLK. However, 2 of us, after downloading all the required files, when we launch the game, and log-in, it says it requires a patch. No biggie, but then when we allow it to patch, we're both getting this error: https://gyazo.com/9b1a005b861c15a7166b98d5b35e5f7a this is the only drive with enough space on my computer to support this. I cannot find a fix on my own, so I'm hoping somebody in the community has run into this issue before, and can suggest a fix.
Thank you :)

DO NOT run it from the Launcher.exe. that will connect to Blizzard and try to patch you up to Retail level. Delete that thing or rename it (Launcher.exe.bak) and run the game from Wow.exe only. If it already patched, or started to and changed files, your install is now borked and you'll have to delete it and get it back to 3.3.5a. Hope you have a back up of your client download!