This Dollmare guide will help you get all 20 notes in Dollmare as well as how to get Ending B.
Day 1
Note 1 – in locker room (there are 2 lockers you can open)

Note 2 – Behind printer in workshop
Note 3 – Under the stairs after the lights go out

Note 4 – In the generator room on boxes

Day 2
Note 5 – Locker on the left in Utility room

Note 6 – Fulfillment room between boxes on the left side

Note 7 – Assembly room on the floor

Note 8 – Assembly room on a table by the broken dolls (I did this before fixing the machine)

Day 3 + Ending B
Note 9 – Under the box across from the locker room on the bottom shelf

Note 10 – Behind the jars of eyes in the repair room
Note 11 – After you have gone down the chute, it will be under the stairs

Note 12 – It is on the boxes as you leave. A little jump will get you there

ENDING B – If you want ending B, after you find the note under the stairs, go through that door. You will have the crouch. Once up the stairs, go left and keep going. Eventually you will find the crowbar voucher. This can be purchased at the end of Day 3 for $1000.

Day 4 + Ending B
Note 13 – At the very end of the hall by the locked stair door, there are some boxes on the shelf. The note can be found there.

Note 14 – In the workshop by the ladder. It is still on the boxes

Note 15 – In the workshop on the backside of the disposal chute

Note 16 – In the repair room on a shelf

Assuming you bought the crowbar, use it to open the door that is boarded shut. Head up the stairs and to the office. Once there, take the doll on the desk and leave the room. Throw it down the disposal chute and continue as normal.

Day 5
Note 17 – On a chair in the locker room
Note 18 – Behind the x-ray machine in the workshop
Note 19 – On the assembly belt line (once you start playing hide and seek with the dolls)
Note 20 – On some boxes next to the generator (once you start playing hide and seek with the dolls)
Day ??? + Ending B hint
Hint to ending B – there is a note in the prison section in the only open cell on the 3rd level after you can drop down a few levels. This is BEFORE you drop down to the lowest level to leave. It eludes to the doll in the directors office. (I don’t think this has anything to do with the achievement, as it popped for me on Note 20)