If self-hosting, usually all you need is a single team, and the way to do that is to set the environment variable GRIST_SINGLE_ORG to the name of the team (should be any short lowercase identifier, such as a company name, using characters a-z, 0-9 and -; e.g. grist-labs or cool-beans).
There are a bunch of steps to run a solid self-managed server. Here’s the best collection of information for that: Self-managed Grist - Grist Help Center.