How do I create a learning category headcount report?

Summary:

I am having to create new reports for the new Learning Subject Area (Workforce Learning - Learning Records Real Time)

due to the Learning Management Subject Area's demise.

Has anyone any guidance on how to create a report showing how many users have completed the Learning Item Category?

If anyone has any reporting using the new Subject Area using the measures that would be really helpful.

Content (required):

Looking to link Ethnicity, AgeBand and Gender from the Person Real Time Subject Area to calculate number of specific employees have started a course, but not sure how I link counts over Subject Areas.