I was wondering what are the requirements to create a cabal

It's not something I'd worry too much about until you've had at least one caballed hero character.

Not that I'm saying that would be a requirement, but I think about that rough amount of CF experience would be necessary to see an idea that fits well into the game or understand why some things might not be good ideas.

Cabal creation is a very big thing in CF, and is usually immortal-driven.

There aren't any OOC requirements, like gather 3 leaders and a bazillion gold.

I'd imagine you'll just have to be a great roleplayer, get lots of immortal attention,

HAVE A REALLY, REALLY WELL-THOUGHT OUT CONCEPT THAT CURRENTLY ISN'T BEING FILLED

and be a great, great, great roleplayer.

So the answer is that youre almost guaranteed NOT to have it happen. Unless you somehow perfectly time your crusade with a spark of interest from the immortals. Coming up with an idea/concept good enough usually requires more than one brain.