How can i get this to work using my own source code editor (VS code)?

Your question is not attached to any specific lecture so I can't really tell what code it is you are trying to run, but based on the error message I assume it involves making AJAX requests or something along those lines. When you request a resource using AJAX it has to be hosted on a server. Browsers generally do not allow you to load them directly from a local file, which I'm assuming is what you are currently doing.

That does not mean you can't test this code locally though, you just need to install a dev server on your machine. I don't use VS Code much myself, but I see that there is a VS Code extension called Live Server that should work well for you.

It is pretty simple to use (just install it and then follow the step by step guide on the page I linked to) and it claims to have CORS enabled by default, which is usefull when you are testing out AJAX calls.