Forza 4 and 5 premium bundle not installing

In this case, you may need to reach out to Forza Support because I can confirm that as long as you have purchased the Forza Horizon 5: Hot Wheels you don't need the Forza Horizon 5 Premium Add-Ons Bundle, the bundle itself includes the expansion but you're just required to have the game installed.

The only ones it allows you to install are forza 4 formula drift cars, forza 4 fortune island, forza 4 lego speed champions and forza 4 best of bond. The others do not appear. This is the description for this bundle.

"Xbox Game Pass members, complete your Forza Horizon experience in both Mexico and Britain with this unmissable offer. The Forza Horizon Premium Game Pass Bundle expands your driving adventures in Forza Horizon 5 with the Premium Add-ons Bundle and in Forza Horizon 4 with the Ultimate Add-ons Bundle. Across both games, you’ll receive FOUR incredible expansions including Fortune Island, LEGO® Speed Champions, Hot Wheels, and the second Forza Horizon 5 expansion once its released. You’ll also be the star of the Horizon Festival with VIP Membership offering 2x permanent race rewards in both games, exclusive Forza Edition cars, a unique flair, free cosmetics, and more. Car Pass expands and upgrades your garage filling it with fun and unique vehicles. Plus, get behind the wheel of iconic James Bond cars around Britain and hone your drifting skills with legendary..."

The screenshot showing "included in this bundle" will only show a few as there are too many separate DLC items in it to list fully as there are 11 separate things in it:

"The Forza Horizon 5 Premium Add-ons Bundle includes the Forza Horizon 5: Hot Wheels expansion, Car Pass, VIP Membership, the Welcome Pack, and the second game expansion once it becomes available.
The Forza Horizon 4 Ultimate Add-ons Bundle includes the Car Pass, VIP Membership, Formula Drift Car Pack, Best of Bond Car Pack, and the Fortune Island and LEGO® Speed Champions game expansions"

But, as noted above, the DLC does not come as part of Game Pass Ultimate...you can buy the Bundle and play without owning the game (ie using the Game Pass version of the game)

I found this strange because the bundle in the website shows all the content for Forza Horizon 4 and 5 as listed in the description
https://www.xbox.com/games/store/forza-horizon-...

Try power cycling your console, usually that helps to refresh all the content and licenses attached to your account

1. Turn off your console by pressing the Xbox button on the front of the console for about 10 seconds, until it shuts down completely.
2. Unplug the console's power cable from the console and from the power outlet. Wait 5 minutes.
Important: Be sure to wait at least 5 minutes. This step resets the power supply.
3. Plug the console power cable back in.
4. Press the Xbox button on your console to turn it on.

After that, try to remove and re-add your profile on the console.

In case you need it, here's how to remove and re-add:

https://support.xbox.com/en-US/help/account-pro...

Also disconnect your router from power for about 3 minutes. Then connect it again an when everything is working, try again

Oh, thanks for clarify.
The bundle itself is not free for game pass members. You get a discount