How to install my iOS 15

Check this link...

Update your iPhone, iPad, or iPod touch - Apple Support

Go to Settings/General/Software Update and report what it says.

Did you notice that they came from the link you posted?

No, I did not notice. I must be more careful in the future!

I'm wait for the day I miss one and it becomes a posting loop.

I'll be watching for you to make the same mistake!