This might pertain to other versions of Paint Shop Pro as well. I don't know. Here's what happened to me:
In 2020 I was still running Corel Paint Shop Pro X7. But I had to make some changes to my laptop that required a complete reinstall of the Windows OS.
When I tried to reinstall Corel Paint Shop Pro X7, I ran into roadblocks while trying to activate it. They kept trying to sell me the new version.
Finally I went into a chat, and learned there that support for X7 has been discontinued, but if I had the serial number AND the invoice number, the chat rep would send me to a download link that worked.
So if something similar happens to you, use the chat, and be ready with anything you can scrounge up from having purchased the product.