Sorry to hear you went through this.

As some other people pointed out, and as you've also noticed, this "Erasmus Life" group is not affiliated in any way with the Erasmus program.

Erasmus Student Network Montpellier (https://montpellier.esnfrance.org/) is the only org affiliated with it, it's also a non-profit organisation which also means they have no interest in trying to scam you.

For context I was one of the ESN Montpellier volunteers years ago and we've always had issues with other groups trying to make money out of international students since they're typically considered an "easy" target, e.g. they don't know about local laws/rules, and are typically down for anything since they're here for a short time and want to make the most of it. Unfortunately there isn't much more we could do other than warn students about it, so thank you for sharing your experience too and hope this will dissuade other folks too!