The Rhino installer is responsible for making sure your Windows installation has everything it needs to run Rhino. This includes the .NET framework and Microsoft Visual C++ Runtime redistributable packages. Because many computers already have these packages, they are not embedded in the installer. They are downloaded as needed during installation.
In order to install offline, however, you need to make sure these packages are available.
From a computer with internet access:
For network-wide deployment
Rhino licenses must be validated before they can be used. For offline computers, you can perform license validation offline.
Rhino will now be successfully validated offline.
Note: For network-wide deployment and using an offline LAN Zoo, the necessary data is presented when you try to add a license to that Zoo. For a Zoo-specific write-up of the preceding instructions, see https://wiki.mcneel.com/zoo/rhinovalidateoffline#validating_offline