Unable to install iOS 18.3.2 on my iPhone 11 Pro Max

Whenever I try and INSTALL (NOT DOWNLOAD) Ios 18.3.2, it will tell me that my internet connection was bad or something to do with internet even though my internet is completely fine. I’ve checked on Apple Support and my phone is definitely a supported phone type (Iphone 11 Pro Max) and has enough storage to download it.

[Re-Titled by Moderator]