Use the customer's file to make a xlsx file in Generic Year format. (sample attached)
If not included, add two rows for stats Available Rooms and Retail Rooms.
The file name is in this format QBODFWBF2020Budget.xlsx and copied to the QBO\Budget\Buddy\Hist2020 folder.
Switch mode to Budget 2020 (which is locked and stays locked).
On the Main Menu in Buddy, there's an option 'Load Budget from Excel File'.
that's it!  

See canned response for file attachment