I’m also seeing this problem. I followed all the steps from support doc BLZBNTBNA0000000C
Edit: I was able to fix this issue! Follow the steps from the “Deleting Battle.net Files” but go further. Delete every folder you see that mentions blizzard or battle net.
First remove the Battle Net app. Delete it and then Empty your trash.
Then, delete every mention of it from your system.
For example, step 3 says to Navigate to the /Users/Shared/Battle.net/Agent/ directory and then delete the agent.db file. Don’t do that. Delete the entire Agent /Users/Shared/Battle.net directory.
Go to ~/Library/Preferences/ and delete every directory that mentions Blizzard or Battle Net. Likewise for ~/Library/Application Support/
After I did this and then reinstalled Battle Net, it worked.