Thanks for using Bitnami. Can you give us more information about what you are trying to achieve? Did you follow any guide? Do you have the link to that guide so we can check it?
As you mentioned,
/opt/bitnami/apps/wordpress/htdocs is the
DocumentRoot directory for the WordPress application. Note this is a PHP application that doesn't have an
index.html but an
index.php file as you can see in its own Github repository linked below
Apart from that, we have a Support Tool that will gather relevant information for us to analyze your configuration and logs. Could you please download and execute it on the machine where the stack is running by following the steps described in the guide below?
How to Run the Bitnami Support Tool
Please note that you need to paste the code outputted by the tool in your reply.