Use your main site (https://foundersnetwork.com) to manage only one site. To do this, navigate to Settings > Reading
On the Your homepage displays select A static page then choose your home and blog index page in the drop-down.
The Homepage is your landing page, its the first page the viewer will see when they visit https://foundersnetwork.com
The Posts page is the Blog index page, it automatically populate your posts from newest to oldest. if you don't have a page named blog yet, please create it and set it as a Posts page
This will separate your blog posts from your pages. As you can see on your admin dashboard the panel for creating Posts and Pages is different, please don't be confused by that.
https://blog.foundersnetwork.com is a different installation (considered as a different site). Your problem now is you need to import these 500+ published blog posts to your main site (
How to move posts from one WordPress site to another
There is no problem with your current setup though, I see a few agencies doing this for some reason e.g. they manage the main site and blog site separately.
If you want it to merge then follow my advice, if you want to keep the current setup then buy a new license so you can validate both your main and blog site.
Hope this shed some lights,