My "guess is" that you do not have a transfer switch installed as part of that "factory ready generator package". So, you'll need the generator, wiring from the generator to the battery, the transfer switch and likely wiring from the transfer switch to the trailer power center and to the generator.
All I see in the first photo is a "hour meter wiring plug" (could also control the start switch, but I'm not sure) and what appears to be "fuel tubing" (supply and return) from your onboard fuel tank.
Unless there's "more wiring somewhere that you haven't posted a photo of" then all I see is a "plug to the hour meter and a fuel line that may/may not actually be connected to the tank"...
So, unless the transfer switch is included in the generator package you buy, you'll need all the wiring/supplies to install and connect the transfer switch to the trailer power center as well as all the wiring/supplies to connect the generator to the transfer switch.
ADDED: The installation instructions manual is available here:
https://www.norwall.com/product_pdfs...stall_2018.pdf
If you haven't downloaded that manual and reviewed it, I'd urge you to take a couple hours and go over everything in the manual. The transfer switch/electrical connections are on pages 50-56