Trouble extracting zip file in macOS
Running

file signal-desktop-mac-1.24.1.zip

in the Terminal outputs:


  signal-desktop-mac-1.24.1.zip: Zip archive data, at least v?[0x314] to extract


indicating that there's some issue with how the zip file is encoded. That explains why unzip may have failed to extract the files from the compressed archive.

However, when attempting to extract via built-in Archive Utility by double clicking, or right clicking and selecting Open, the archive extracts successfully.

I tried it, successfully extracted Signal.app and was able to run it.