Aight bois, seem a lotta fellas asking bout this so i'll inform you without spoiling it. First, on round 12 you'll get the ghost bit*hes and the final one will drop the key for the church. After this you'll need to find 2 skulls around the map that have there mouths open (some might get confused becasue there are a lot of skulls on the map) After that take the skulls to the graveyard and place them in the coffin.. some memes will happen.. then head back to the graveyard and pick up the key for the box outside the stables. after this you'll need to find 3 numbers placed around the map (can be very difficult to find) to enter the stables (dere is pap) after doing this you'll be able to go into the portal to start the main quest. wont go into details about that as its fun figuering these memes out for yourself but i'll leave a hint (looks the the roofs using the bow)

edit: the skulls have no pick up option, you'll have to find em and press F to check if they are the right ones