On the downside, if you are self-hosting, Zulip requires a dedicated server (or VM). There are some efforts to make it run in a container but nothing that works really well.
We (the Zulip core community) recently adopted the main third-party Docker implementation for Zulip (now https://github.com/zulip/docker-zulip), and have been hard at work on cleaning it up and making its documentation high quality.
It's not at the level of polish we want it to be yet (which is why we recommend the "dedicated machine/VM" installation flow, which is super polished). But we expect the Docker setup to be quite nice in a couple months.