Hello! I think it would be so much easier to use the SUMIF Function in excel for a conditional sum of values.

The way to use SUMIF is:

=SUMIF(range, criteria, sum_range)

range - range of where you will check the critiera
criteria - the condition where you will check whether to add the value
sum range - the range to be summed based on the condition


So it will easily add all values based on the condition you set. Hope this helps!