Assuming Names in A and count in B within the sheet of Caseload Test workbook and ‘Cases’ (edit to suit ) is the sheet name within the workbook ‘Pipeline Test’ then….

Eg in B2

=COUNTIFS('[Pipeline Test]Cases'!I2:I1000,'Caseload Test'!A2,'[Pipeline Test]Cases'!M2:M1000,"Yes”)

and copy down.