* Error: PayPal Express Checkout is not setup on this account.
If that's the case, make sure that it's not due to having Test Mode enabled. In order to use the PayPal sandbox… you need to signup for a developer account with them.
Also, here are the required variables to enable PayPal Payments Advanced, as stipulated by PayPal
PARTNER The Payflow partner. The example below uses PayPal since PayPal Payments Advanced includes a PayPal merchant account.
VENDOR The Merchant Login ID that you use to log into PayPal Manager.
USER The name of the user whom you added to your account using PayPal Manager, above.
PWD The password of the user whom you added to your account using PayPal Manager, above.