I can't understand the Monastery puzzle...
Humm, what does "25 55 45 N 80 9 17 W" reminds you?
Maybe this might help you[www.google.com]
The answer is SPANISH.

What to do with that tape? I can't find anything logical to write...
Humm, what do you hear in the tape? Try saying it to Bundy.
The image of "Lend an Ear" achievement might help you.
The answer is TRAIN.

Insistent
When the game starts, don't accept the call from Unknown contact three times in a row.

Anastylosis
You get this after you discover the code on the coin (2513).

Invisible ink
The envelope has a page with lemon scent. It's invisible ink, you have to heat it up to read it.

Ponce
The letters on the letter spell PONCE.

WC?!
After you get the clue PONCE, Bundy will tell you about Weird Cases. Ask him "Weird Cases?".

Fountain of Youth
After Bundy tell you about Weird Cases, he'll show you a map of Florida. Select the Fountain of Youth Hotel to get this achievement. I don't know if you have to select it first to get the achievement or not.

Surgeon
To remove the paper from eye socket, select the tweezers.

Hi-tech cartographer
The word missing on the paper found during autopsy is SPANISH.

Scrolls and Ancient Kings
When Bundy sends the photo of Alphonse VII, select the symbol you found at the girl's bedroom.

Lend an Ear
The killer wanted you to hear the TRAIN in the audio tape. Observe that if you say NO (thus skipping the puzzle) you won't get the achievement.

Brick by Brick
It's written BRICK in the ring.

Gotcha!
When you complete the game.

Golden Laurel
I don't know the exact requirements of this achievement, since when I got it, I couldn't decipher the tape puzzle and the significance of Monastery to the killer.

Prankster
These are the choices that led me to this achievement.

• Accept request
  
• No, and I don't want to know anything about it.
  
• Now is not the right time.
  
• Buy a car!
  
• The desk
  
• 2513
  
• Was there a finger?
  
• The postman's cologne
  
• Call forensics
  
• PONCE
  
• What did he say?
  
• Select Fountain of Youth Hotel
  
• Wait for backup
  
• About time!

The last choice unlocks the achievement.

Enthusiast
These are the choices that led me to this achievement.

• Accept request
  
• I am the right person
  
• I can't wait!
  
• See you later, partner.
  
• Examine the window, the bed, and the desk.
  
• 2513
  
• Tell me everything
  
• Invisible ink
  
• Heat up
  
• PONCE
  
• What did he say?
  
• Select the hotel last
  
• Enter, quick!
  
• How's it going?
  
• Let's analyse the sockets.
  
• Select any other tool, except tweezers
  
• Do you have the results?
  
• And the card?
  
• SPANISH
  
• He's an artist
  
• Select anything except SYMBOL
  
• There was another victim
  
• Let's get to work
  
• Blowtorch?
  
• Let's analyse the audio tape
  
• TRAIN
  
• BRICK
  
• It's the right place.

The last choice unlocks the achievement.

Dry Laurel
These are the choices that led me to this achievement.

• Accept request
  
• No, and I don't want to know anything about it.
  
• Now is not the right time.
  
• Buy a car!
  
• The desk
  
• NO
  
• Was there a finger?
  
• The postman's cologne
  
• Strong light
  
• NO
  
• What did he say?
  
• Select Fountain of Youth Hotel
  
• Wait for backup
  
• About time!
  
• Select the hotel last
  
• Enter, quick!
  
• About time!
  
• Let's analyse the sockets.
  
• Select any other tool, except tweezers
  
• Do you have the results?
  
• And the card?
  
• NO
  
• He's an artist
  
• Select anything except SYMBOL
  
• There was another victim
  
• Let's get to work
  
• Blowtorch?
  
• Let's analyse the audio tape
  
• NO
  
• NO
  
• It's a long shot.

The last choice unlocks the achievement. I suppose this achievement is unlocked by saying NO as an answer for the 5 puzzles, but, if needed, all choices are listed here.

https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2828035227
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2612860117
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2314011325