Hi, I wanted to try using Clip Studio Paint, and remembered I had an old serial number from buying Manga Studio EX 4 from years ago. After installing the latest version of CSP on Windows, I tried entering the serial number but it would ask if I mistyped the code instead, even though I checked the number many times. I looked for answers online, and they suggested to install version 1.6.2, but that version seems to be unavailable to download anymore. I don't know if the problem is that the serial code is so old, or because I may have used it already years ago (unfortunately I don't remember if I had an old account I used back then). Please let me know if there's any way I can still use my old serial number, thank you!