The Secrets of Dr. Wu is not only a more content pack, it's also a campaign extension to the main JWE campaign. To get the features the DLC has (Advanced Storm Defense Tower, new genes, business upgrades, and dinosaurs like the Troodon and Stegoceratops) you have to play through the campaign extension in the main campaign to do so, just like how you unlock everything else in the normal gameplay.
This extension becomes available once you get at least 4 stars on on Isla Muerta. Once you've done that, the next location on that island, "Isla Muerta East", becomes available and, from that point, you can start unlocking that DLCs stuff from there. Complete that island's missions, and you can unlock even more stuff on the "Tacano Research Facility".
However, to progress that latter map, you must have at least all the required dinosaurs from the main game from the other five islands available to you.
That's how you get the stuff from the DLC. To sum it all up:
1. Get 4 stars on Isla Muerta (while on Muerta itself and not on any other island, even if it may have 4 stars already)
2. Play through Muerta East as you would with the other islands
3. Complete all of Muerta East's missions, the Tacano Research Facility becomes available
4. Play through Tacano Research Facility as you would with the other islands (albeit with a couple of unique perks)
5. To progress the latter map's missions, required dinosaurs from Matanceros to Sorna the map's missions require must be unlocked for use first
So, I think you guys actually do have it in your game, no bugs or anything like that. Just do the following I listed above, and you will be able to activate the campaign extension and unlock its content for your son's game.
