To unlock the Ledger inRDR2, you need to go to the Contribution/Donation box in your camp (Horseshoe Overlook, The Hearthlands, NH) and Give all the Debts. After, you can find the ledger to the right of the contribution box at Dutch’s tent....
After completing Chapter 2: “Money Lending And Other Sins” (given by Strauss), you will unlock the ledger. You can then put money in the tithing box and upgrade the camp. Buy the two camp upgrades in the lodging category: “First Things First” ($220) and “Next In Line” ($325)...