I have downloaded the latest version. But not able to install it. It’s seeing an error. Pls tell me how to install it.

To update over the air from the phone all of these requirements must be met:

• You need at least 6 GB of free storage
• You must be connected to a Wi-Fi network (and not a personal hotspot) unless it is an iPhone 12 or 13 series with an active 5G network connection
• The phone must be charged to at least 50%, and preferably plugged in so it stays above 50% during the update
• The phone must not be in Low Power Mode
• The phone must not be connected through VPN
• The phone cannot be in Airplane mode
• You cannot still have a beta version installed on the phone

If you can't meet all of them you can still update using your computer.

Hello,

See this:

Updating iOS: common issues and solutions

Good luck.