After rescuing the captive near Vagalala he says I can get money from a cache behind the big shrine in Vagalala cemetery.

I did find a small box there, when I focus on it 'Ground' is displayed on screen (like for gear dropped on the ground). I have a 'Inventory' action in the action menu and when I open it sometimes it is empty, and at some point I can open it again and find the money roll.

As a guess, there are maybe multiple 'ground' stashes there and it's difficult to open the one containing the money. At first I couldn't find the money so thought was a bug. But later I tried again and did open the inventory and found the money roll item.