Everything is explained in the mod description regarding installation

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SPOILERS
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Abandoned Shop
When Wendy asks you to find the holotape in the abandoned shop, you can
find Jack's diary in 'Jack's Duffle Bag, next to the safe in the corner of
the back room.

Allertons Bunker Passcodes
0 - found above the vault, use the stacked tables to climb on top.
1 - In the dining room, in a picture frame
2 - In the kitchen store room, wedged between Cram I believe.
3 - (upstairs) On a wardrobe in a bedroom
4 - (upstairs) On a music stand in the music room
5 - (upstairs) through the door and up the stairs of the parallel entrance to the bunker