Error installing personal gateway

Not sure about if it will work with only 443, but it is only outbound ports that need to be open, it does not require any inbound ports. Not sure why your security folks would configure their firewalls to block outbound ports but security folks tend to be intractable and singularly unreasonable, particularly ones that don't actually know what they are doing and thus just "block everything" by default because "it's more secure that way". Blocking outbound ports is, theorectically, a way to mitigate the damage of an exploit once it has found a foothold within your system. Of course, modern day exploits tend to use well known and almost certainly open ports (like 80, 443) in order to "phone home" these days so the real benefit of this is pretty questionable. Might save you from an exploit by an idiot hacker but if they are an idiot hacker, they probably didn't get past your defenses to implant some malware in the first place.

Stepping off of soap box...

I believe that the installer is most likely trying to contact a site to see if there are any updates to the installer package. That IP Address is registered to Akamai which is a Content Delivery Network (CDN). So, perhaps just open up that IP or Akamai IP's in order to get the installation to go through.