[Koha] How to place orders as grants i.e free of charge from vendor

Our library has just installed Koha version 3.4 for our use and I'm using the Acqusition staff client module to place orders for a special grant to our library. I have already entered the Vendor details however the system keeps asking for the budget. These items are received as grant or donation and thus does not require budget. Appreciate any help to enable progress with the acquisition. Kind regards, Luisa Korodrau Librarian Davuilevu Theological Library Nausori Fiji