Loop until quantity needed met - count in multiples based on item

Hello,

I'm looking for a macro that can go down the list of items in the "Need" sheet, determine how many repeats of that item based on the "count by" sheet, and put the result in sheet4. The macro needs to do this for every item in column A of the "Need" sheet.
An example of the result I am looking for is the "desired output" sheet.

Thank you for any help!