In order to start creating passes, you will need to create some certificates and service credentials:
- Log into your Apple Developer Console and select Certificates, Identifiers & Profiles.
- Select Identifiers from the menu on the left, and select "Pass Type IDs".
- Follow the instructions to create a Pass Type ID and remember the identifier.
- Generate a certificate according to the instructions shown on the page.
- Download the .cert file and drag it into Keychain. In Keychain, select both the certificate and the private key under it, then right-click and choose "Export 2 items...".
- Choose a password and remember it.
- Store the exported .p12 certificate in a non-publicly accessible folder.
- Download the G4 WWDR certificate from https://www.apple.com/certificateauthority/. It can be exported from Keychain into a .pem file.
- Follow the first 3 steps of the following manual to gain access to the Google Pay for Passes API: https://developers.google.com/pay/passes/guides/basic-setup/get-access-to-rest-api
- Store the service account credentials JSON file you downloaded in step 2 in a non-publicly accessible folder.