Ken said: "I have found the old installation files and, as I have CS6/ID8 still installed and working on my desktop PC, thought I had found the serial number. However, it only has 20 characters and not the 24 sought."
Hi Ken,
maybe you found the wrong serial number.
Let me explain this a bit more:
For some years now InDesign CS6 and InDesign CC version 9 are not part of Creative Cloud anymore.
That means: If you took the serial number from the old installation and you had installed CC software on top of it you have the wrong serial number extracted, because the CC installation back then changed your perpetual serial number to a new one that is tied to the Creative Cloud.
And that means for your new machine:
First wipe all creative cloud software from your machine, then install your perpetual version with your perpetual serial number. You cannot retrieve that serial number from a machine where you installed creative cloud.
To get rid of all remnants of a creative cloud installation use the Creative Cloud Cleaner Tool:
https://helpx.adobe.com/in/creative-cloud/kb/cc-cleaner-tool-installation-problems.html
Regards,
Uwe Laubender
( ACP )
{Response modified by MOD}