Why can’t I install my downloaded software update?

To update the phone check these requirements:

• The phone must be charged to over 50%
• Low Power Mode must be OFF
• You cannot be connected through VPN
• You must have a Wi-Fi connection (not cellular)
• While not a requirement per se, you should plug in the phone or put it in a wireless charger to assure it stays on and connected to Wi-Fi

Can you Force ReStart your iPhone and try again? Here is how to Force ReStart your iPhone-->>Force restart iPhone - Apple Support

Good Luck.

Axel F.