I used VLOOKUP for years, and then I started having difficulty making it work.

So I switched to SUMIFS, as it was easier for me to figure out and get the results I wanted.

The formulas are:

=SUMIFS(sum_range, criteria_range1, criteria1, [criteria_range2, criteria2] ...)

=VLOOKUP(lookup_value, table_array, col_index_num, [range_lookup])
Range_lookup: TRUE if numbers (1) or FALSE if text (0)