Hi @tobimahony
You can aggregate all records into the array.
Iterate and deduplicate the array of IDs (Klasse_ID). This way, only unique IDs will be output.
Set multiple variables - ID (Klasse_ID) from the iterator and the number of occurrences (count) in the original array from the first aggregator (=in the data store) using the set of functions with the use of the iterated IDs and date (Angesehen am) below.
Finally, you can aggregate them to get a new array of IDs and their count you can use anywhere further in the scenario flow.
I hope it makes sense 