Unable to install update

Hello Reemaljudayi.

Thank you for using Apple Support Communities. If you're receiving an error while attempting to update your device, we'd like to help. We have a great resource that you can review for when facing errors while trying to update. Click here: If your iPhone, iPad, or iPod touch won't update - Apple Support

These steps might be able to help out:

1.) Restart your iPhone.

2.) Try updating your device again using the same network.

3.) If you see the same error message, try updating using a different network.

4.) If the same error populates on multiple networks, remove the update.

5.) If issue isn't resolved, update using a computer

Just in case, the following resource can also guide you through steps you can try to update via a computer:

1.) Update your iPhone, iPad, or iPod touch with iTunes - Apple Support

2.) Update your iPhone, iPad, or iPod touch with the Finder - Apple Support

We hope this information is helpful. Cheers.