When I try to download it, it says:

“Attackers might be trying to steal your information from download.scratch.mit.edu (for example, passwords, messages, or credit cards).”


I'm not really sure if it's safe or not to download. Does anyone know?

I think that Scratch didn't renew their certificate for the download website so Google doesn't know if it's safe. It should be alright though.

It's fine. It's warning you about a possible security breach, but the actual chances of one there are fairly small.

Websites have a certificate to prove that the servers behind them are who they say they are. The ST hasn't renewed the certificate for download.scratch.mit.edu, so it's possible that it could be impersonated, although unlikely.