Hello fellow zee captains!

I just bought the zubmariner expansion, I synced the content (It said "new stories available", I downloaded those), but when I loaded my safe, I didn't have the "Under the Unterzee" quality that basically unlocks the dlc content.
So I decided to cheat it into my inventory with safe file editing, which seemed to work at first, it allowed me to do the quest up until you get your zubmarine, but now I have another problem. It says "press T to transform", but pressing T doesn't do anything. I've tried different locations, remapping the transform key to something else, nothing seems to work.
Do I need to start a new captain for it to work (since I did it kinda cheat-ishly) or am I missing something obvious?

Thanks in advance!

UPDATE: Okay, so I completed the game with my current captain, hoping everything shall be well for the next one. It wasn't, nor was any manner of thing well.
For starters, I again didn't have the "Under the Unterzee" quality, although the "A Zubmarine Zecret" quality from my previous playthrough did carry over. I went to port Carnelian and had my ship upgraded, but again, pressing T doesn't seem to do anything.
At this point I'm thinking there is some kind of problem with the game not detecting that I have Zubmariner, even though I do and have (presumably) downloaded its content through the authentication system.

EDIT: Also in the authentication screen I only see 2 things: Sunless Sea (the base game) and "A whisper-locked puzzle box" (a reward from Fallen London), but no Zubmariner DLC.

I figured it out, and feel kinda stupid now.
Turns out I had to download the dlc installer separately from my gog library and install it the old fashioned way. Why there is no option to install it with gog galaxy is unclear to me, but whatever.
Case closed.