I purchased the podcast and forum access at
https://permies.com/wiki/219079/Paul-Cancer by clicking on the link in an email sent to the email address associated with my account.
I guess I made the mistake of clicking on purchase with Paypal, which is already logged in, and which has a different email address associated to it. Which means the purchase is not linked to my account.
Any way that my purchase can be linked with my account?