Hi Jessica,
This component allows the usage of Vonage Services called via APIs. Below you can see the definition of these webservices to be consumed on Service Studio:

In order to use these services, you will need Vonage credentials (under the form of an API key and a secret) so the service provider can identify who is using these services and (probably) bill according to your use as a client.
That is why you need to provide those site properties in order to make it work, even if it is a demo.
This is a very common pattern which you can find in services like Google Maps as well.
To get these values, you will likely want to create a Vonage account and see which kind of plans it serves best your intentions (they have a free trial), but you can read more on their website. On the screenshot below of the Vonage website, you can see the Get an API Key on the right top corner to request one:

Hope it helps.
Cheers,
João