Error installing Omeka-S: can't get to admin

Hi! I’ve followed the instructions in the user manual to install Omeka-S, but have hit a wall. I’ve uploaded the files to an /omeka-s directory in my server’s html folder, they’re all writable, readable and executable by www-data as far as I’m aware, and I’ve put the SQL user (who has all permissions for this db) and database info in database.ini. But when I go to /omeka-s/admin, I get an ERR_CONNECTION_REFUSED (on https; on http I get a 404). What could I be missing here?

Thank you!