The code is within Teng's notes. She says in her notes that she used a rotation cipher to encrypt the code, and that the rotation key is the minute digit of the note time.

A rotation cipher works like this: you take each letter, and substitute it with a later character in the alphabet.

So with rotation cipher key 2, "ABC Hello" becomes "CDE Jgnnq"

Does that make sense?

Omg, this part was extremely frustrating. I just figured it out. It's "The Admiral Is Foolish". I wish there hadn't been a random encryption puzzle in the middle of a dialog based text adventure. It felt so out of tone with everything else.

Ok, jumping back in to finish the game. I'm honestly loving it, but I couldn't leave someone else with the same question hanging.

I'd recommend spoiler tagging that, in case anyone else wants to solve it themselves. I tried to word my post so that people could solve it without being spoiled.

Beside rotating letters, you can guess what the answer is from the choices based on the amoutn of letters if you split the encrypted word by just looking at the capital letters.

For example if it says AbcDefgHijklm

Abc = 3 letters so pick the choice with 3 letters.
Defg = 4 letters so pick the choice with 4 letters.
And so on.

Yeah , some puzzles broke the immersion at times; especially when one has to google rotation/caesar cipher to get a better definition. More detailed explanations could have helped with some of the puzzles (even if just in hints).