Where is root folder of Wordpress blog?

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I am trying to integrate my YUNOhosted Wordpress blog with the fediverse but it is currently not being detected. Others have signposted the Activitypub plugin developer’s FAQ which says that ‘in order for webfinger to work, it must be mapped to the root directory of the URL on which your blog resides’. I am trying to follow their instructions at:

The problem is that I cannot find the root directory of the URL on which my blog resides or either of files which are referred to in the FAQ. Where is it?
If anyone can guide me I would be very grateful.

YUNOhost version 11.0.10.2
Installed on bought VPS
User skill level: Beginner; I can use the web admin, navigate directories via ssh and edit files using nano

The wordpress root directory is on /var/www/wordpress (or wordpress__2 if you have a second instance, etc.)

The NGINX configuration is in /etc/nginx/conf.d/$YOUR_DOMAIN.d/wordpress.conf

Thank you so much!