Skedler Alerts user role should have the following privileges on configured with Xpack:

Cluster Privileges - monitor

User Indices Privileges - read, view_index_metadata

Index Privileges - .alert* - all

Index Privileges - alert_history - all 

You can set up the Alerts user role privileges in your kibana UI under Management > Security > Role.  as shown below,

Set the alert_elasticsearch_username and alert_elasticsearch_password properties in alertconfig .yml with the x pack username and password created for the skedler-alerts role. Enable ESSecurity_user_login to yes for user login as shown: