Quick note not working

QuickNote in iPadOS15 is not supported by iPad Air2 and iPad mini4.

QuickNote requires an iPad with an A9 CPU or later. The Air2 has an A8X CPU, whereas the mini4 has an A8 CPU.

Info buried deeply here:

https://www.apple.com/ipados/ipados-15/

The 2014 iPad Air 2 and 2015 iPad MIni 4 DO NOT SUPPORT the Quick Notes feature.

The Quick Notes feature needs an Apple A9 CPU, or greater.

An iPad Air 2 has a lesser Apple A8X CPU and the iPad Mini 4 has an even lesser Apple A8 ( NO X ) CPU.

So, NO Quick Notes feature

This info is found in the iPadOS/iOS features page for the section on Quick Notes and in the iPadOS/iOS 15 gray footnotes at the bottom of the Apple Website Webpage.

Here are screenshots below from that page.

Sorry.