The problem on Dreamhost isn’t if you can edit .well-know/webfinger, but that when you have the ActivityPub extension added to your WordPress install, WP takes over management of the file and keeps it elsewhere, so you have to edit the .htaccess file in the .well-know/ directory to redirect any ActivityPub service that tries to check your webfinger can find where WP is keeping it.
The .htaccess file that Dreamhost defaults to in that directory looks like this:
# Permit access to the challenge files but nothing else
Order allow,deny
Allow from all
RewriteCond %{REQUEST_URI} ^/[.]well-known/acme-challenge/[a-zA-Z0-9_-]+$
RewriteRule .* - [L]
RewriteRule .* - [F]
I changed mine to look like this:
# Permit access to the challenge files but nothing else
Order allow,deny
Allow from all
RewriteCond %{REQUEST_URI} ^/[.]well-known/webfinger+$
RewriteRule .* /wp-json/activitypub/1.0/webfinger [L]
RewriteCond %{REQUEST_URI} ^/[.]well-known/acme-challenge/[a-zA-Z0-9_-]+$
RewriteRule .* - [L]
RewriteRule .* - [F]
I hope this helps!
