If you already have WordPress installed but are being redirected to the WordPress installation page you may have an issue with your database or configuration file. In this article I will go over some potential solutions to help you restore access to your existing WordPress site.
This type of issue is most frequently caused by the use of an incorrect WordPress database table prefix. What you need to do to correct this is to ensure that the $table_prefix variable within your wp-config.php file matches your actual database table prefix.
You can check your existing database table prefix via your servers cPanel or phpMyAdmin. Once you know your database table prefix (note that the default is wp_) you can then check the $table_prefix variable within your wp-config.php file. If they do not match, simply edit the variable as needed.
In the image below you will see that I am using the following table prefix variable (wpqv_) within my wp-config.php file and that my database tables match that variable. If this were to change, WordPress would prompt me to install itself again.
The reason for the database table variable is so that you can have multiple WordPress installations within the same database. For example wp1_, wp2_, wp3_ and so on and so forth.
I welcome your thoughts, questions or suggestions on my article on solving why WordPress is asking to install itself again.
Let me know if you found any errors within my article or if I may further assist you by answering any additional questions you may have.