When accessing the page to download I got a warning from safari/chrome saying that it's a harmful software with a red page. Where can I download it safely ?
That's common with all mining software, it's a false warning. If you check out the details you'll probably see it tagged as 'potentially unwanted program' which is fine if you download it on purpose.
but where did you get this false warning from? It seems to me that Google is not so stupid
This is a recurring problem because miners get bundled with malware so companies like sophos mark them as 'potentially unwanted programs' and google flags the pages. It should be fixed for my downloads now though as I contacted them and pointed out it's not malware but I wouldn't be surprised if it gets auto flagged again at some point in the future.