After you donate, there is a button on the PayPal page that says “Return to Merchant.” Scroll down if you don’t see it.
This is what it looks like:
But I missed it the first time!
If you missed the button the first time, you may need to recreate your buttons. When you are asked to donate you can donate as little as 1 cent to get your code. You can also contact me for a refund of your original donation.