Freesound library

What you get is an installer, and it is not signed. A code-signing certificate is bought rather than earned, and this one has not been bought yet — so Microsoft Defender SmartScreen does not recognise the publisher, and says so before it will run the file:

1. Your browser may stop the download itself. Choose Keep.
2. Running it raises a blue Windows protected your PC box whose only button is Don’t run. Click More info.
3. Click Run anyway.

That box means SmartScreen has not seen this publisher before. It is not a report of anything found in the file — but it is not nothing either, and every release publishes a checksum so that you can check what you downloaded rather than take this paragraph’s word for it. The installer writes to your own user account, so Windows will not ask for an administrator.

The AppImage is one file that needs no installing and no root. Mark it executable and run it — on some distributions it also wants FUSE 2, which is libfuse2 or libfuse2t64 in your package manager. The .deb is for Debian, Ubuntu and anything built on them: sudo apt install ./<the file>, and the app arrives in the menu like any other. Either can update itself in place afterwards.

Linux will not warn you about any of this, which is worth saying out loud rather than leaving as a pleasant surprise. Nothing here is signed by a distribution, nobody has reviewed it into a repository, and the checksum below is the whole of what stands in for that.