If you work without a USB dongle, Vectorworks automatically connects to an online server. This connection must be made at least once every three months. This means you can use Vectorworks without an Internet connection for a maximum of three months.
The available libraries are not downloaded to your computer by default during installation. If you want to use a Vectorworks library, you need to download it first. Once the library is downloaded, you no longer need an Internet connection to use it.
You also need an Internet connection (temporarily) to update your Vectorworks license or libraries.