You have 60 days to withdraw from your purchase and get your money back, and that holds even after you have downloaded the PDF. You don't need to give a reason, and I won't ask for one. The first 14 days of that are your statutory right of withdrawal. The rest of the time I give you on top of it, and I hold to it just the same.
Send me an email to info@bjoernwindorf.com with "Withdrawal" in the subject line. Include your order number from your confirmation email. A clear statement is enough. There is no form to fill in.
The guides are sold through Digistore24, so Digistore24 GmbH, St.-Godehard-Straße 32, 31139 Hildesheim, Germany is the seller on your invoice. You can send your withdrawal there as well, at support@digistore24.com. Either way reaches me. Write to whichever is easier for you.
Your money comes back promptly, at the latest 14 days after your withdrawal reaches me, to the payment method you used.
Eine deutschsprachige Fassung findest du unter Widerrufsbelehrung.