When using acquisitions in Koha you first need to define some defaults.
Set up your funds & budgets
Choose your default currency and enter others if you order from multiple countries
Enter in your vendor information
Create an Framework with the code ACQ (if you're going to enter item records at the time of ordering or receiving)
Acquisitions System preferences
AcqCreateItem : Decide if an item record is created during acquisition
CurrencyFormat : Decide how you want monetary amounts to display
gist : Enter your sales tax (if you are billed for tax)
OrderPdfFormat : Decide what format you want your print orders to use