Please tell how to do so ?
You first need the code from ‘upi’ which you can then inject into your document using Footers
See the following guide for more details:
https://www.manager.io/guides/footers
I’m using Manager 24.1.19.1287
In the Custom field, I don’t see the option for QR Code. Only Text, Para or Dropdown. I suppose one could enter the QR code image as a HTML. Is that possible? How?
please update

There is as @Syed_Salman_Ali already alerted to no purpose in reporting that a feature does not work in an outdated version. See FAQ - Manager Forum specifically:
Manager advances very quickly, simplifying and adding features and capabilities. Sometimes, bugs occur with new releases. But these are usually fixed rapidly, often within minutes. So if you encounter a problem with the desktop or server editions, update Manager , even if you recently did. (The cloud edition is always up to date.) You can check the latest version at https://www.manager.io/desktop/download/ .
Thank you for understanding that this is needed to avoid discussing issues that may have been resolved in more recent versions.



