my app store download keeps asking to confirm with assistive touch. what is assistive touch?

This explains Assistive Touch --> Use AssistiveTouch on your iPhone, iPad, or iPod touch - Apple Support

To turn off Assistive Touch:

• Tap the Settings in the iPhone home screen to launch the Settings menu.
• Tap General > Accessibility.
• After seeing the Accessibility Settings menu, tap the option Assistive Touch.
• As the Assistive Touch Settings screen opens, slide the slider from On to Off to disable the Assistive Touch feature, which will turn from green to gray.

Glad to help. One way to avoid odd quirks after an iOS update is to immediately Force Restart your phone as soon as the complete completes.

If you don't know how, this link explains how --> Force restart iPhone - Apple Support