The language of renting in Austria

This article from The Local might be very helpful to those with limited German: https://www.thelocal.at/20210406/the-words-you-need-to-know-before-renting-a-flat-in-austria/

It explains words like (Der) Mietvertrag, (Der) Altbau and Neubau and even...gulp...(Die) Mietschuldenfreiheitsbescheinigung

The article is probably behind The Local's paywall but I think you are allowed to read one or two articles per month so you could try accessing it from a different browser to usual or, better still, subscribing to The Local.