Unable to activate iPhone 11 Pro Max

You may just be out of space on the phone. Look at your Settings -> General -> About on the phone. If your space available is less than 15% of the capacity, you have run out of space.

You can on a Mac use Image Capture to download all movies and photos from a phone.

There are utilities that let you download all your texts and voice mail to your Mac as well.

Keep in mind, your carrier may not be storing that info off your phone, so you'll want to backup any data on your phone before you perform an update.

updating the phone is best done while attached to a Mac, using the utility on the Mac after a backup has been done.

https://support.apple.com/en-us/HT204204

Hello Gibberishmew,

It sounds like you are unable to activate your iPhone due to an alert that states an update is required. We understand how important this is to you and we are here to help.

You have attempted some great troubleshooting steps. Let's attempt to update your device again, since that is what the alert states. This article should help: If your iPhone, iPad or iPod touch won’t update

If the issue persists, can you provide a few more details? Do you know which iOS version is currently installed?

Good Luck!