To achieve Core Implementation Accreditation you need to have gained your Implementation Fundamentals Accreditation.
You will then need to complete the following virtual instructor led course, there is no free self-paced e-learning option for this class.
Cluster Administration - Required Course
This 3-virtual day course is for an experienced Splunk Enterprise administrator who is new to Splunk Clusters.The course provides the fundamental knowledge of deploying and managing Splunk Enterprise in a clustered environment.
It covers installation, configuration, management, and monitoring of Splunk clusters. While Splunk Clusters are supported in Windows environments, the class lab environment is running Linux instances only.