Hi @chrda81, and welcome to OpenZiti.
As you can see by the commit history, the ziti-sdk-js has been dormant for a couple years. This particular SDK should not be considered viable at this time.
It will most likely be reborn as ziti-sdk-browser (yes, spelled with an s not a z). This would be the SDK to manually embed within your web app, if you elected not to use our automatic web-app-Zitification enabled by the broader browZer stack.