It has broken editor integration (Zed) though at least for the time being. But the CLI works. Hopefully that's just a temporary thing -- as much as I like working in the terminal, this is a bit awkward.
Vibe keys seem to be somehow different from other API keys: I wasn't able to create a working key manually, but when navigated via a link that Mistral Vibe gave me, things started working. Or at least I think that was the reason.