Instagram Highlights are not a bulk download
A Highlight is a Story the account chose to keep on its profile. This site does not offer a highlights viewer, and it does not download a whole highlight album from a profile URL. Pasting a username or a profile will fail.
What does work is a public Story that is still live, if you have the story link itself and the story opens without logging in. Use the Instagram Story downloader for that link. Once the story expires, the highlight on the profile is not a substitute this tool can open.
Close-friends stories and private accounts stay closed. No password is asked, and there is no bypass. A normal public post or Reel is a different link. Use download Instagram videos for a feed video, or the Reels downloader when the URL contains /reel/.
If you need the file, save the Story while it is public. Do not expect a highlight circle on a profile to behave like a video post. Personal use only, and only when you have the right to keep the file.