Flatfile Portal 2.0 does not support using a URL directly as a source for data. To use a URL, you will need to use `fetch`.
The code to do so should look something like this:
const csvRequest = await fetch(csvUrl)
source: await csvRequest.text()
The ability to do this is only possible in Portal 2.0 at this time, not Portal 3.0 or Workspaces.