UPDATE: I used the following two links to gain an understanding of what was causing the error:
https://linux.101hacks.com/unix/client-denied-by-server-configuration/
https://httpd.apache.org/docs/current/howto/htaccess.htm
I had to correct my .htaccess file, as the line of code was causing the error code. It had to be changed to Require all denied. After I did that, the error code went away. Woohoo!