Serial Number prompt Windows 11

I'm sorry to be blunt but Ultradev is a relic from a bygone era.  It's no longer fit for modern use and should not be used in 2022. 

• It has zero support for modern HTML, CSS & JavaScript code;
• zero support for responsive web design;
• I doubt it will open much less recognize LESS, SASS, SCSS, SVG or JSON files. 

You really need a new code editor.  If not Dreamweaver CC (sold by subscription) then something other than what you have.

CODE EDITORS:
-- Adobe Dreamweaver CC - https://www.adobe.com/products/dreamweaver.html
-- Atom (free) - https://atom.io/
-- Codespaces (free, browser-based) - https://github.com/features/codespaces
-- Nova (Mac only, formerly called Coda) - https://nova.app/
-- Pinegrow - https://pinegrow.com/
-- Sublime Text - http://www.sublimetext.com/
-- Visual Studio Code (free) - https://code.visualstudio.com/
-- Wappler ~ Visual Web App Builder - https://wappler.io/

You either need to run a virtual machine with Windows 98/2000 or it's time to upgrade DW from Ultradev. Just be thankful it ran as long as it did without crashing.

My computer does not allow Windows 11 to be installed. It is too old. Conversely, a 22 year old product will not install on Windows 11. Think of it: 32 bits compared with 64 bits. It is impossible.