In order to setup Apple Pay on your Braintree and Magento 1 store, you will need to -

1. Purchase our Apple Pay module

2. Register your domain in the Braintree control panel - see Sandbox or Production instructions (note: you do not need to setup certificates)

3. Enable Apple Pay in the Magento Admin, under "System Settings" - "Payment Methods"

We advise testing Apple Pay on a production account - if using a sandbox account you need a sandbox iCloud account which can be purchased through the Apple Developer program.