There’s a few options depending on your requirements. Checkout options 2, 3 or 4 in Prevent development server getting indexed by google - #2 by digitalstartup. If it’s just during development then I tend to use option 4.
However, in reference to the code you’re referring to - You need to swap out
<Directory "/opt/bitnami/apps/APPNAME/htdocs">
with your actual web directory where you have Magento install. So, if you’ve been following along with my guides/tutorials then this would be /var/www/html/`, so the line would be:
<Directory "/var/www/html">
And then this next line will vary depending on the apache configuration locations (whatever you ahve it set as:
AuthUserFile "/opt/bitnami/apache2/APPNAME_users"
Note: The instructions refer to a very specific type of setup. Probably One-Click Install in either a Shared Environment of one where something like cPanel/Plesk is installed? I don’t work on these environments so my knowledge is lacking on troubleshooting them.