An APN (Apple Push Notification) certificate is used by ERA MDM for iOS device enrollment. First, you need to create an Apple-provided push certificate and get it signed by Apple in order to enroll iOS devices to ERA. Also, make sure your ERA has a valid license.
Click the Admin tab > Certificates > Peer Certificates, click New and then select APN Certificate.
Specify certificate attributes (Country code, Organization name, etc.) and click Submit request.
Download your CSR (Certification Signing Request) and a Private Key.
Once you have completed all the steps above, you can create a Policy for MDC to activate APNS for iOS enrollment. You can then Enroll any iOS device the same way as an Android device - by visiting https://<mdmcore>:<enrollmentport>/enrollment from the device's browser.