I haven't used Bullet Train, but I've found their "Teams should be an MVP feature" blog post [1] a really great overview of how to model team structures in relational databases before. Worth a read!
nice! that's something i stumbled over when re-architecting a 2-sided marketplace (in rails) for one of my startups. the data model they describe is roughly what i ended up with, but it took some iterating to get there. the key understanding was that the relation table in a many-to-many relationship is not just a technical detail but encodes important information about real world systems, especially the human kind. as engineers, we get often get stuck on the entities being the important bits, but more often, the relations are where all the action is.
I really like Derrick Reimer's blog[0] for these types of posts. You might have to go back in time to find something a little more technical. On second glance, it seems the older articles are no longer available. You can find most of them[1] on the Wayback Machine though.