The error means exactly what it says: Hugo needs layout files to know how to render your site and its contents. It cannot find one compatible with the “home” page for the “HTML” output format: Template lookup order | Hugo
What does your config look like? Your _index.md? Do you have your code somewhere we can have a look at? It’s difficult to diagnose just from your directory structure. Have a read about Requesting Help as well, to make it easier for us to help you.