While it might be nice if there we pre-rendered tiles available for download, and openmaptiles.org constantly steers users to "buy now" pages, instead of offering a simple button to the self-service docs, they do in fact offer a significant amount of documentation on how to generate and serve your own tiles[1], including a page with fairly step-by-step instructions on how to create a tileset "from scratch" without sending them a cent[2].

1. https://openmaptiles.org/docs/ 2. https://openmaptiles.org/docs/generate/generate-openmaptiles...