pre-existing WP site install on test-site loses all content & styles

I’m re-vamping a pre-existing website (eileenmyles.com).
The site is constructed in PHP but is not primarily a WordPress site.
It has a WordPress subfolder, however, called ‘blog’, containing all WP files for this section.
The link to the orig site (i.e. not the test site) is eileenmyles.com/blog/ – this opens the WP part of the site.
I’ve installed all site files, including ‘blog’ WP files onto another site as a subdomain so I can revamp it and test it there while orig site remains up.
Test site is at ‘eileenmyles.ceciliadougherty.com’
In order to access the ‘blog’ section, I’ve reconfigured the wp-config file to reflect the test site location so I can work on the ‘blog’ pages of the site.
WP install worked fine and I can access ‘blog’ page, which I could not do before reconfiguring wp-config file.
Wordpress ‘blog’ subfolder is at ‘eileenmyles.ceciladougherty.com/blog/
Problem: I’m seeing a completely new WP site. The site files that are in place for the ‘blog’ are not connected. Header & nav bar, images, content, plugins – all are in the proper folder, in place and uploaded, but none are activated.
How to activate the new WP site with it’s pre-existing files?