As everything related to visionOS is still in beta it probably wont be included in public releases. The release candidates are usually a 100% how the public release will be. So betas like visionOS aren't included. So for now you have to use the previous beta for visionOS, but there also should be a new Xcode 15.X beta soon (probably next week), that again - because it's a beta - also includes the visionOS beta.

I also have the same issue. I was able to update to Xcode 5.1 (15C65) trough the App Store, but installing the iOS Simulator 17.2 fails with HTTP error code 403.

Seems fixed for me now. I'm finally able to download the iOS Simulator 17.2.