I am facing the same difficulty.
Thanks for using View SDK, sorry to hear that you are not able to get it to work and appreciate you sharing addional details about the issue. Usually this error occurs when we use invalid/incorrect client id or using correct client id in wrong domain etc. We need more details to debug further, request you to check your console network logs and confirm if the viewlicense call is failing like below.
I resolve it.
It was a problem with my web security trousted sources.
I'm also having this issue. I can't add localhost to the allowed domains list for the API key and I get a 401 Unauthorized error when trying to preview locally. I know I don't have an issue with the incorrect client ID since I only have the one. Seems like a lot of people are having this localhost issue and it's a major blocker for development.