hello:
1.Here are the steps to do in the ONTAP web interface

https://docs.netapp.com/zh-cn/active-iq-unified-manager/config/task_configure_audit_logs.html
2.Whether it is necessary to store audit logs, this depends on the requirements, the advantage of audit logs is that the security is particularly high, when there is a failure, you can quickly locate the cause of the failure, the disadvantage is that it will occupy a certain space in storage, and you need to clean up the audit log regularly