Excel - Formula to find multiple variables

If you have upgraded to 365, this should do what you want:

=LET(
u,UNIQUE(B2:D19),c,INDEX(u,,2)&INDEX(u,,3),
BYROW(F2:F3,LAMBDA(r,LET(a,FILTER(c,(INDEX(u,,1)="A")*(INDEX(u,,2)=r)),b,FILTER(c,(INDEX(u,,1)="B")*(INDEX(u,,2)=r)),
SUM(BYROW(a,LAMBDA(r,--ISNUMBER(MATCH(r,b,0))))))))
)