Lots of options for what might be happening:
- Create an account first. Being logged in solves a number of problems.
- Smart devices on certain browsers, from time to time, don’t work with WooCommerce (the platform here for purchasing). Try a computer for the purchase; you still should be able to view lessons on your device.
- If you’re in a Nordic country, use zip code 0000. I don’t know why but that usually works. If not, try a different browser or device; we have yet to figure out the combination that is causing the problems. (And let us know if you figure it out!)