Hey @atharwa first of all, my apologies for the delayed response 
we’ve taken a little time off at the end of summer and I’m catching up at the moment.
These are the latest Circle installers: PIB Customers: Latest Circle Installers {2.2.1}
To activate, you just need to copy / paste your activation code when it prompts you.
Do you still have your activation code? If not, I can look for it in our database, just send me a DM with your email address.
We added the user accounts to our site around 2018 I think, so it’s very possible that you don’t have an account set up if you made your purchase before then.