Flattening export file

I'm trying to get an exported data file of our daily transactions into a format I can import into Quickbooks. It groups a transaction by customer and I need to get the customer name changed to a column and filled down for each transaction. It also needs some cleanup. Is there a way to automate this? Any help would greatly be appreciated.

I've attached the raw export I get from our POS system (Export Data.xlsx) and the format I need for Quickbooks (Import Data.xlsx).
Export Data.xlsx Import Data.xlsx