Instagram now requires login to view most content, including stories. But there are ways to view stories without any account at all.
Instagram changed its policy in recent years, requiring users to log in to view content. This means you can't open profiles or stories without an account through the regular app or website.
DarkViewer doesn't require any account or login. Just enter the username of the person whose stories you want to see, and the tool will display all their current stories with download options.