Curator and ILM can coexist. However, to prevent Curator from accidentally interfering, or colliding with ILM policies, any index associated with an ILM policy name is excluded by default. This is true whether you have a Basic license or not, or whether the ILM policy is enabled or not.

Curator can be configured to work with ILM-enabled indices by setting the allow_ilm_indices option to true for any action.

Learn more about Index Lifecycle Management here.