Thanks, I got a bit confused with terminology. I only deal with the backend stuff of websites about once a year.
I set up the WordPress multisite to use subdomains, though now I wish I did it as subdirectories. Didn’t really understand the choice at the time. The Pressbooks instructions don’t say much about that stage.
The public_html folder is the one with the wp-config.php file, so I did edit the correct htaccess file.
Tried using the above example htaccess, but everything looks exactly the same.