The off the shelf Postgres drivers work. We're a pure Postgres extension so you don't need anything exotic there just a standard Postgres driver. When it comes to the application side of things it depends a little bit more there on how you may structure your queries. To help out there we have a few libraries (for Rails[1] and Django[2]) and more coming.
[1] https://www.citusdata.com/blog/2017/11/14/scale-out-your-dja...
[2] https://github.com/citusdata/activerecord-multi-tenant