Hi, please go to https://www.mozilla.org/en-US/ where you can find all our products and download them from there for your platform!

Since you posted this thread in the Firefox for IOS (iPhone/iPad) section you need to install on the Apple App store.

https://support.mozilla.org/en-US/kb/install-firefox-your-ipad-iphone-or-ipod

The KB article says you need iOS 13.0 at minimum when the minimum has been iOS 15.0 since the Fx 120.0 Release