hljhljhlj are there any errors in the browser console, PHP-FPM or Flarum logs? Could you share the output of php flarum info
and possibly your Nginx configuration too?
Remember that we can't help you if you don't provide the community some details to work with. Also, the configuration is indeed from 2016, and Flarum has changed a lot since then - it is expected that it won't work as intended anymore, and someone will likely need to update it