There's a TEMPLATE for this example. CLICK HERE to crceate a new project using the template.
If you have your Gumroad notification email sent to Conducttr you can parse the sale value and buyer's email address - creating a new audience record, incrementing their total purchases today and unlocking the experience.
Use this as your matchphrase in the email trigger
|parse('decimal') as sale| && |parse('email_address') as buyer into audience.3rdparty.accounts.email|
This will take email address and create a new audience record if one doesn't exist. Note that we're using "3rdparty" because it's the referenced email inside the message and not the sender (which would be Gumroad)
Also use 3rdParty in the Modify: row and use the variable |sale| to increment the audience attribute.