Hi,
>>"I have an activation code from Autodesk LT 2011"
No, you have a requestcode and you WANT an activationcode.
You have to ask AutoDesk and not other users like you!
If you have installed on XP Professional or Home edition (SP2 or later),
perhaps you have luck and Autodesk activate it one time more,
but in other situations - I have less hope.
https://www.autodesk.com/support/download-install/individuals/product-key/determine-whether-you-need...
https://ava.autodesk.com/modular/
https://forums.autodesk.com/t5/previous-version-support/bd-p/6051