This may be my favorite thread here ever, many laughs. And no one on either side, the generous knowledgeable volunteer experts nor the hopeful new Flarum user, will learn anything from it. Yet everyone means well.
Someday when I install 2.x under Hestia Control Panel I will do what I always do with Flarum after 3 years running a forum -- ask Claude.ai and keep sending "him" the error messages and descriptions until after many iterations an hour or two later, somehow, with a method impossible to document or recreate, it will finally work with proper permissions and folder security.
My best guess is that the "public" folder concept is needlessly confusing and ambiguous, since most control panels have an existing public_html folder. To dramatically simplify adoption, there should be a standard automatic installation method that simply always works and creates whatever needs to be created by brute force. Fancier install variations could then be left to those who are Linux gurus.
Way more complex software just works, why can't Flarum? It's easier to install and use Docker, Portainer, Caddy, Paperless-ngx, Immich, Navidrome and FileGator from scratch than "simple, light" Flarum.
It takes a non-guru to understand how non-gurus think.