"recommended-project" installs drupal into the /web subdirectory, but hosting solution directs traffic to webroot
When you use the drupal/recommended-project template to create a Drupal project via Composer, you can use a different directory for the server document root.
Instead of running composer create-project drupal/recommended-project my-project:

Run composer create-project drupal/recommended-project my-project --no-installation
Edit the composer.json file found in the my-project directory to replace any occurrence of web/ with public_html/
Inside the my-project directory run composer install
Copy the content of the my-project directory (including any subdirectory) into the directory containing the server document root directory

This is described in Using Composer to Install Drupal and Manage Dependencies.

If you want to modify some of the properties of the downloaded composer.json before composer install is executed, use the --no-install flag when running composer create-project. For example, it is possible that you want to rename the subdirectory 'web' to something else.
To do that:

Run composer create-project --no-install drupal/recommended-project my_site_name_dir
Change directories to my_site_name_dir and edit the composer.json file to suit your needs. For example, to change the sub-directory from 'web' to something else, the keys to modify are the 'extra' sub-keys 'webroot' and 'installer-paths'.
Run composer install to download Drupal 8 and all its dependencies.