That's the Plan, Padre

While in the basement of Sammy’s bar, the huge safe there will become accessible and the place will be transformed into your stash house. It’s not a good idea to carry a lot of cash in your wallet since you’ll lose a huge part of it if you die. To avoid this, make it a habit to store your hard-earned cash in the safe before engaging in a dangerous mission or gunfight. The money you have stored in the safe and the amount you have in your wallet are cumulative so even if you purchase an item exceeding the amount you have at hand, the remaining balance will be deducted from your money in the safe.

After storing your cash, leave the building and follow the mission marker to a motel where Donovan temporarily set up shop. Enter the room to the far left on the second floor to find Donovan and trigger a long cutscene. Lincoln’s road to revenge has begun. The next mission will start.