There is currently one requirement to start your database project development in ADS, it is that you need the Insider build of ADS (that you can download here). After the installation, you’ll need to install the extension. Please search for it in the list of extensions and install it in your ADS instance.
Tom Norman and I talked about it in detail on last night’s episode of Shop Talk (to be posted later today). It’s a good start, but there are still some rough edges and missing functionality. I’d expect that to improve over time, though.