Counting Unique Values

I am building a participation tracking system and got stuck. We have RFID badges that can be scanned into Excel to track attendance. I have set up that part with no problem. I am trying to set up a dashboard to easily see attendance. I currently have all scans going to a table so I can turn them into pivot tables for the dashboard. However, since my system tracks every instance of attendance a value is counted more than once. Example, 1 person attends an exercise class on 7/27/2020 and then attends the same class again on 7/29/2020. It will show up that the resident attended the class twice, which is correct and I want to track that. However, I also want it to show that the 1 person has attended the class from a historical perspective. I need help to be sent in the right direction for formulas so that I can 2 things: There were a total of 10 attendance for this class and it was attended by 4 different people.

I know this can be completed using countif and sumproduct but I want this to be shown on 1 single dashboard that is able to be filtered by slicers.

Thank you