Open the Identifiers page and use the blue + button to create a new App ID.
Apple Developer Portal - Identifiers
Select the App IDs option and click Continue.
Apple Developer Portal - Register new identifier
Enter a Description for your App ID.
Note: The description is purely for your own reference and is not used outside of the Apple Developer Portal.
Enter the Explicit Bundle ID of your app.
Note: You can obtain the Bundle ID from AppMachine by following steps 1-4 in this article.
Apple Developer Portal - Register App ID
Scroll down the list of capabilities and enable Push Notifications.
Note: Do not add any other capabilities. Capabilities need to be supported by the app's software. Enabling unsupported capabilities may cause issues during or after your app is published.
Apple Developer Portal - Enable Push Notifications capability
Click Continue to proceed with your App ID registration.
On the next page click Continue and proceed without providing Deployment Details.
Apple Developer Portal - Deployment Details
Check the settings of your App ID once more before finishing the process by clicking Register.
Apple Developer Portal - Confirm App ID registration