I see, because when I enter the website all I see is the info button, but on some other devices I see a second qr code and the models at the bottom but no launch AR button
That's also intended. It depends on if the device supports Augmented reality.
For PC and Mac, you will see the QR code, as you can't use augmented reality on those platforms.
For Android and Quest, you will see a button that says View in AR, as augmented reality is supported directly in the browser.
Where as for iOS, at least on the newer models, you should see a button that says Open with Launch AR.