10.14.2 here too. I don’t want my Mac downgraded, I want that freaking game working 
I have the exact same problem. On both High Sierra (10.13.6) and Mojave.
SC2 does not install as well! Behaviour is different however. It is simply stuck on waiting… after confirmation of installation.
D3 and HoTS does install with no issues… 
What ?
I can install Heartstone aswell.
Same here, worked fine before I updated my battle.net… Also works fine on windows… same network… …
There’s something up with this patch.
A summary:
On Windows, Bitdefender and Adaware both prevent it from downloading the manifest since 8.1 prepatch came out.
Apparently the Macs error out on install, rather than constantly trying to do initiate over and over again (which is worse, hogs bandwidth).
Other updates seem to work, Battle-net, Hearthstone, D3, HotS – as above, Starcraft 2 might also have an issue (not tested that myself).
Just installed latest updated from Apple that was released some days ago and I had been too busy to install it.
I’m now on macOS 10.14.2 (18C54)
I do not know, if this fixed it, but It seems to be installing now! Screenshot take.ms/EUe5u
Strange, I’m running the same version and it wasn’t working for me 
Try again, because I haven’t changed a thing and it seems to be working now.
Before installing OS update, I removed battle.net client and attempted to install wow from outside battle.net eu.battle.net/account/download/
This basically reinstalled the client and ended up with the same exact behaviour. THEN I decided to just update the OS version… after ~20 minutes it booted, battle.net opened and the installation just continued without issues.
I admit. This is really strange!
Lol it actually started to work
Why would this issue be affecting such a limited audience? Is it Bitdefender trying to stop malicious application(s) during this update or is it Bitdefender (and Adaware) itself that is a problem during the update procedure?
Given it only kicks in on this specific update from Blizzard, I’m assuming it is doing something that the AV doesn’t like. I’m surprised there are not more people affected by it, or at least not more complaining. There are a fair few here, but Bitdefender has millions of users, would’ve thought more WoW players would have issues. Might be some combination of issues in play, or lots of people not reporting the problem.