This pattern is based on a square spiral granny square blanket I first learned from a tutorial by Krysta of the Secret Yarnery. Watching that tutorial, even though it is on a square blanket, might be useful: youtube.com/watch?v=3W6EX-gQXcM&t=985s

Recommended yarns, gauge, finished size are all nonsense. Do what you want. None of that matters, although it does work best with two yarns that complement each other. If you use lighter weight yarns, use a smaller hook. If you use heavier yarns, use a larger hook. Your own eye is the final judge of success.