Generate an Apple Push Notification Service (APNS) Certificate

A push notification certificate is a type of digital certificate that allows your Apple TV to send and receive push notifications from Apple's servers. To send and receive push notifications from Apple's servers, you must generate the push notification certificate for your Apple TV and iOS devices. Push notifications are a way to send messages to your Apple TV even when it is not in use. For example, you could use push notifications to send messages to your Apple TV users to remind them of an upcoming event, or to send a notification when a new episode of a show is available. For more information, refer Apple's Keychain Access User Guide, and you may also refer to this Medium article for more insights. 

To create a push notification certificate, you will need to:

1. Choose “Example TV” identifier. This is the identifier that will be used to identify your Apple TV on Apple's servers.
2. Next to Push notification, click Edit > Create Certificate.
3. In create certificate screen, there will be an option to upload Certificate Signing Request (CSR) file.
4. If you don’t have a CSR file with file extension .certSigningRequest, then follow these steps to generate a new one:
   a. From the Keychain Access app on your Mac, navigate to Certificate Assistant > Request a Certificate From a Certificate Authority.

        d. Then a screen will open up, enter your email id and select the Save to Disk option. Then you can save the CSR file:

6. On the previous step where it asked for a CSR file, please upload the one you just created and proceed further with certificate generation.
7. Once the certificate is generated, extract the .p12 certificate from Keychain Access.

A .p12 file is a password-protected archive file format that is used to store digital certificates and private keys. It is also known as a PKCS#12 file or a PFX file. The .p12 certificate is the file that you will need to install on your Apple TV.  To install the certificate, follow the instructions that are provided by Apple here.

Once you have installed the certificate, you will be able to send and receive push notifications from Apple's servers.