Excel: Sum Values in a Column for Rows Where a Particular Value is Matched in a Corresponding Cell

I have two sheets in Excel: (1) one with the data I'm continually adding to and (2) one that reports on a variety of metrics.

I want to use a formula in (2) to display conditional counts of data in (1). The formula should show the sum of numerical values from a column (T) when the corresponding row values in another column (B) match a value from sheet (2).

The values in column B vary. I'm also continuing to add data to sheet (1), so I can't specify different arrays for each column (B) value I'm trying to look up.

For example, in the picture below, I want to return the count of values from column D that correspond to values in column A when the value in column A matches the value in another cell on a separate sheet. So, on a separate sheet, when the cell matched appropriately, "Josh" would return "2", "Karen" would return "1", and "Brad" also "1".

This isn't the data I'm actually working on, but I think it demonstrates the concept.

I've tried combinations of vLookup, Dsum, Sumproduct, with IF statements. I feel like there's something obvious I'm missing. Help!