Formula to add rows based on required capacity

If I understand correctly then the following will do what you want:
1) The following formula in G5 and down references the number, picked by data validation in cell H3: =IF(ROW(1:1)<=H$3,ROW(1:1),"")
2) The following formula in the range H5:I24 will copy the data from columns C:D based on whether or not there is a value in the corresponding row of column G: =IF($G5<>"",C5,"")
Let us know if you have any questions.