Hi again,
Their response was as below...
"Thanks for writing! I was able to locate your registrations in our database, but it looks as if you did not create a Single Sign-On account with Cakewalk prior to the company's closure in 2017. Back in 2014, Cakewalk had advised users to migrate any previous registrations to their new account platform that would combine the web store, the user forum, and features from cakewalk.com all within one account to log into. This system was in place from mid-2014 until Gibson ceased operation of Cakewalk in 2017.
If you have the original discs, you can install as normal. Right-click on the desktop icon and choose Run as Administrator, then enter the codes as seen above to activate the program!
While we cannot assist with account creation on the legacy Cakewalk site, we're thrilled to have announced that Cakewalk by BandLab is free for 64 bit Windows 7, 8, and 10 users! This is our continuation of the previous flagship SONAR Platinum and is a current software receiving updates and support."
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I can confirm that I did not create a Single Sign-On account with Cakewalk back in 2014, as Cakewalk did not inform that I had to.
Cheers!