"Apple cannot check it for malicious software": what should I do?
It means the app isn't notarized, so Apple hasn't scanned it for known malware and can't vouch for it. That doesn't prove it's harmful, but if it came from an ad, a pop-up or a stranger's link, click Move to Trash. Only open it if you're sure the source is trustworthy.
Notarization is a free check Apple runs on apps sold outside the App Store. Gatekeeper, the part of macOS that checks downloads, shows this stronger warning for apps without that stamp. Notice there's no Open button, just Done and Move to Trash. A small, honest developer may simply not have notarized an older tool, but scammers rely on people pushing past this.
If you trust the app, there's a way to open it. After you try once, go to System Settings, Privacy & Security, scroll down and click Open Anyway, then confirm. Before you do, ask: did you go looking for this app on purpose, did it come straight from the maker's own site, and is there an App Store version instead?
- If it came from an ad, pop-up or unknown link, click Move to Trash
- Look for the app in the App Store or on the maker's official site
- Be suspicious of any site that explains how to get around this warning
- Only if you fully trust it: System Settings, Privacy & Security, Open Anyway
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Gatekeeper and Notarization
From the Gatekeeper & App Safety course. How your Mac checks a downloaded app before it opens.