Who can help me with my issue?

I would like to summarize all fields in the coumn C that apply to given
'text' values in colums A AND B.

I tried VLOOKUP, but this is only applicable to the first value and limited
to two columns

SUMIF is more flexible but I cannot find the formula to first select the row
where both values in column A and B apply and only than the value in the
third column of the same row is added to the values in the next row with the
same match.