Why Am I Getting An Error At Task `Enable Automation Hub rhsm repository` When Installing Ansible Automation Hub?

Issue

When installing Ansible Automation Hub, it caused errors.

TASK [repos_el : Enable Automation Hub rhsm repository] *********************************************************************************************************************************************************************************************************************************************************************
fatal: [host01.example.com]: FAILED! => {"changed": true, "cmd": ["subscription-manager", "repos", "--enable", "rhel-7-server-automation-hub-4.2-rpms"], "delta": "0:00:03.175759", "end": "2021-01-28 20:07:58.795570", "msg": "non-zero return code", "rc": 1, "start": "2021-01-28 20:07:55.619811", "stderr": "", "stderr_lines": [], "stdout": "Error: 'rhel-7-server-automation-hub-4.2-rpms' does not match a valid repository ID. Use \"subscription-manager repos --list\" to see valid repositories.", "stdout_lines": ["Error: 'rhel-7-server-automation-hub-4.2-rpms' does not match a valid repository ID. Use \"subscription-manager repos --list\" to see valid repositories."]}
...ignoring

TASK [repos_el : Explain Automation Hub rhsm repository failure] ************************************************************************************************************************************************************************************************************************************************************
fatal: [host01.example.com]: FAILED! => {"changed": false, "msg": "The rhel-7-server-automation-hub-4.2-rpms channel could not be found on this system. Please ensure this machine is registered and subscribed to Red Hat Ansible Automation Platform subscription."}