Problem in doing Dynamic Segmentation of the data

See if this works for you...

To calculate the number of transactions by employee:

Number of transactions by User ID =
VAR _ID =
    MAX ( Spending_Data[Emp_ID] )
RETURN
    CALCULATE (
        COUNT ( Spending_Data[Date] ),
        FILTER ( Spending_Data, Spending_Data[Emp_ID] = _ID )
    )

To calculate the number of employees by number of transactions

Employees by number of transactions =
VAR _Table =
    COUNTROWS (
        FILTER (
            VALUES ( Spending_Data[Emp_ID] ),
            [Number of transactions by User ID]
                = SELECTEDVALUE ( 'Credit Card Used Filter'[Credit Card Used Filter] )
        )
    )
VAR _4Plus =
    COUNTROWS (
        FILTER (
            VALUES ( Spending_Data[Emp_ID] ),
            [Number of transactions by User ID] >= 4
        )
    )
RETURN
    IF (
        SELECTEDVALUE ( 'Credit Card Used Filter'[Credit Card Used Filter] ) > 3,
        _4Plus,
        _Table
    )

To get

Link to file:

https://1drv.ms/u/s!AhGKDZz6e4HehKh1p8KY73_fpvAapA?e=ucajGn