Took me a bit of time to track this one down but I think I've figured it out.
Not working and Problem: The current download under "For Business" > "Emsisoft Command Line Scanner" contains a2cmd.exe file version 184.108.40.20670 and after extracting the zip file and trying to perform the update (a2cmd.exe /u) I would receive the following message:
"Could not connect to the update server. Please check your internet connection or proxy settings."
Working: The current download under "For Home" > "Emsisoft Emergency Kit" after running the executable has a2cmd.exe file version