On Macs, Safari has several built-in protections that may block file downloads or cause incomplete transfers. This can happen if your storage is full, the internet connection is interrupted, you have outdated OS or Safari versions, or interfering plugins/extensions are installed. Check your available storage space and clear up a room if needed. Make sure your Mac OS and Safari are fully updated. Try disabling any Safari extensions to isolate if one is causing download blocking, then remove any problematic plugins.