Why is «Enable this Solution» backend control disabled for the «PayPal Express Checkout» payment method?

What does <requires> tag mean in a backend config field XML declaration?

To enable the «Enable this Solution» option you should:

  • Fill the credentials fields:
    • «Email Associated with PayPal Merchant Account»
    • «API Username»
    • «API Password»
    • «API Signature»
  • Disable other PayPal payment methods («Website Payments Standard», etc.)
  • Disable «Enable PayPal through Braintree» option for the Braintree and BraintreeTwo payment modules

See also: