Toast 18 Registration Error - Possible Firewall block

[Stoopid David]

I tried to register a new copy of Toast 18 Pro today, but the installer gave me an "unknown error" after I entered the key#.  It's entirely possible that I need to whitelist something in our corporate firewall in order to allow the registration through to the internet- (Our machines have no internet access, save for whitelisted sites).  I allowed roxio.com and Corel.com, but it still doesn't work.  Roxio support says Toast won't work on a corporate network- but that sounds like an uninformed answer to me.  Does anyone know how to properly whitelist Toast's activation server so we can use this product?  It's running on macOS 10.13 High Sierra.