Five Nights at Freddy's: Security Breach

There are 50 collectible messages in the game needed for this achievement. Almost all messages are found by collecting dufflebags throughout the map (the Hello Gregory message is automatically given to you shortly after receiving the Fazwatch).

A list of dufflebags/messages in the game can be found on the FNAF wiki

https://freddy-fazbears-pizza.fandom.com/wiki/Dufflebags

You can see which messages you have under the messages tab on your Fazwatch, and compare to the list on the wiki to see what you have and what you need to get. Some messages aren't accessible without the upgrades from Monty and/or Chica, so you can't get this achievement prior to 6 AM. Unlike the prize boxes, dufflebags aren't visible through walls using the Roxy upgrade.

For whatever reason, the wiki doesn't list all of the dufflebag locations, and the ones missing from that list are:
1. Red Flag - found in the backroom of the Glamrock Salon (same room as the Princess Quest cabinet).
2. BBW Maint Log - found on one of the seats in the Daycare Theater (same level as the stage).
3. Behind the Maze - found in the Security Office of the Monty Gator Golf area.
4. Chica Report - found in Chica's room in Rockstar Row, in front of the door to the charging room.
5. Safety Check - found in a hallway behind the diner counter at Bonnie Bowl.
6. Ultimate Party Host - found in the West Arcade, in the same room where you repair the STAFF head from Roxy Raceway (far left corner from the entrance door)