The Premature Extraction
By default, Apple configures the Safari web browser on macOS to be overly helpful with downloaded files. When you download a compressed archive (like a .zip or .rar file), Safari utilizes the built-in Archive Utility to automatically extract the contents the moment the download finishes. It then usually deletes the original compressed file, leaving you only with the extracted folder. While this saves a double-click for simple downloads, it is incredibly problematic if you are downloading a .zip file that you intend to email to someone else, or if the archive contains potentially unsafe executable files that you wanted to scan before opening.
Disabling Safe File Opening
To maintain control over your archives and stop macOS from automatically unzipping files downloaded through Safari, you must disable the browser’s “safe files” setting.
Open the Safari browser. In the top menu bar, click on Safari and select Settings (or Preferences on older versions of macOS). A new window will appear. Ensure you are on the General tab (the first icon on the left). Look all the way down to the very bottom of this General settings page. You will see a small checkbox labelled Open “safe” files after downloading. (Apple defines “safe files” as movies, pictures, sounds, PDF and text documents, and notably, archives). Click this checkbox to uncheck it. You can now close the settings window. Safari will now leave all your downloaded .zip and archive files exactly as they are, requiring you to manually double-click them to extract the contents.