On the website, click “Register.” You will be taken to a secure payment processor (FastSpring or PayPal).

Go to the official payment portal (FastSpring or PayPal). Pay the $59.

If you’re looking for legitimate help with Soundplant:

Download the official free version from soundplant.org . Test it. Make sure it works with your audio interface and keyboard.

Regarding the registration code, if you've purchased the software, you should have received a legitimate code via email or other communication channels. If you're having trouble with your registration code, I recommend contacting the official support team for assistance.