Mietkaution services?

I keep getting ads from ImmoScout about this DirectDeposit alternative to a regular Mietkaution. Are these legit? For someone coming from outside of Germany, is there a real advantage? Or is it a scam? I‘m kinda freaked about forking over the deposit …

https://www.immobilienscout24.de/umzug/service/mietkautionsrechner.html?cmp_id=10-03685&cmp_name=relocation_deposit&cmp_position=residential_expose&cmp_creative=criteria