Using Zorin OS Pro entitles the Pro user to get direct installation support from the ZorinGroup.
The ZorinGroup consists of two people... And they are also actively developing Zorin OS 17.
Pro User Contacts can end up in a queue if things get really busy. Most likely, the Zorins have not yet gotten down to your message in the list, yet.
I would think running that in terminal would only result in it saying "Package not found"
I cannot think of a single package command that will install all of Pro. The ZorinGroup might know of a command to use.
You might try:
sudo apt install --reinstall zorin-appearance-premium zorin-appearance-layouts-support zorin-os-layouts-shell-premium zorin-os-desktop
After running the above, be sure to watch for prompts in the terminal to set up GDM as your display manager - login manager.
Once it is all done, from the Login screen, click the gear icon to log in on the Gnome Desktop.
You might check the "Upgrade Zorin OS" app again from within that desktop, if necessary...
Here is a list of the additional software that comes with Pro: